Large GO Proposals are those that request 75 orbits or more.

Large Programs should lead to a clear advance in our understanding in an important area of astronomy. They must use the unique capabilities of HST to address scientific questions in a comprehensive approach that is not possible in smaller time allocations. Selection of a Large Proposal for implementation does not rule out acceptance of Medium Proposals to do similar science, but target duplication and overall program balance will be considered.

Approximately 1250 orbits are available to new Large and Treasury Proposals in Cycle 26. Descriptions of previous programs are available on the Treasury, Archival Legacy and Large (TALL) Programs webpage. Most Large Proposals accepted in previous cycles were allocated between 100 and 150 orbits, though larger orbit requests are welcome if scientifically justified.

Data taken for all Large Programs have no proprietary period as a default. Proposers may request a proprietary period, and that request should be justified in the ‘Special Requirements’ section of the proposal. Such a request will be subject to review by the TAC.

Investigators submitting Large Proposals should consult the Large Program Scheduling User Information Report linked from the HST Documents page and the HST Orbital Viewing and Schedulability page. These documents contain necessary information for developing a Large Program that is feasible with respect to HST orbit scheduling. Proposers should include additional technical detail on the scheduling aspects of their program in the ‘Description of Observations’ section. The shorter orbital visibility will be enforced in Phase II for each approved Large Program.

As with Medium Proposals, detailed Program Management Plans are required with the budget submissions.

Long-Term GO Proposals

Medium, Large, and Treasury GO Proposals may request HST observing time in more than one cycle if a clear scientific case is made.

Long-Term Proposals must be limited to cases where long-baseline, multi-epoch observations are clearly required to optimize the scientific return of the project.

Long-Term Proposals require a long time baseline, but not necessarily a large number of HST orbits, in order to achieve their science goals. Examples include astrometric observations or long-term monitoring of variable stars or active galactic nuclei.

You may request time in up to three observing cycles (26, 27, and 28). Long-Term Proposals should describe the entire requested program and provide a cycle-by-cycle breakdown of the number of orbits requested. The Cycle 26 review panels and TAC will only be able to award a limited amount of time in future cycles, so a detailed scientific justification for allocating time beyond Cycle 26 must be presented. Scheduling concerns are not a sufficient justification. The sum of all orbits requested in Cycles 26, 27, and 28 determines whether a Long-Term Proposal is Medium or Large (or counted against the Cycle 26 orbit pool in the panels). Target-of-Opportunity Proposals are eligible to be Long-Term if certain conditions are met.

GOs with approved Long-Term Proposals need not submit continuation proposals in the subsequent cycles (and hence, GOs who had Cycle 26 time approved in Cycles 24 or 25 do not have to submit a Phase I continuation proposal, although a new Phase II and budget submission will be required for each cycle).

Budget requests submitted for the first cycle of a Long-Term Proposal should include costs only for the effort to reduce and analyze the data obtained in the first cycle. Separate budget proposals are required in each subsequent cycle; see Grant Funding and Budget Submissions.

Treasury GO Proposal

Treasury Proposals are those designed to create datasets of lasting value to the HST project that should be obtained before HST ceases operations. A Treasury Program is defined by the following characteristics:

• The program should focus on the potential to solve multiple scientific problems with a single, coherent dataset. It should enable a variety of compelling scientific investigations.

• Enhanced data products are desirable to add value to the data. Examples are reduced images, object catalogs, or collaborative observations on other facilities (for which funding can be provided). Funding for the proposed data products will depend on their timely availability, as negotiated with the STScI Director. They should be delivered to STScI in suitable digital formats for further dissemination via the HST Data Archive or related channels.

• Data taken under a Treasury Program will usually have no proprietary period (see Data Rights), although brief proprietary periods may be requested if that will enhance the public data value. Such requests are subject to TAC approval.

The following additional characteristics are particularly encouraged:

• Development of new techniques for observing or data reduction.

• Creation and dissemination of tools (software, web interfaces, model, etc.) for the scientific community to work with the data products.

The emphasis in Cycle 26 remains on observations whose value is maximal if taken soon. However, Treasury Proposals may request observing time to be distributed in future cycles if scientifically required (similar to the situation for Medium and Large Long-Term GO Proposals). In this cycle approximately 1250 orbits of HST time will be available for new Large and Treasury Proposals. Descriptions of previous Treasury Programs are available on the HST Treasury, Archival Legacy and Large Programs webpage.

Treasury Programs will be selected by the TAC as part of the normal peer review process. Successful proposals will be reviewed by STScI to ensure observing efficiency. STScI resources may be made available to approved Treasury Programs by decision of the STScI Director. In particular, some programs require substantial pipeline processing of their data to generate the final products. Examples are large mosaics for surveys, or co-additions of many exposures in deep fields.

Investigators submitting Treasury Proposals must select the Treasury Program flag on the APT cover page, use an orbital visibility that enhances schedulability (use the Increase Schedule Flexibility flag in APT), and include additional technical details on the scheduling aspects of their program in the “Description of the Observations” section. Note that a proposal can be both Large and Treasury. Submitters of Large Treasury Proposals should consult the Large Program User Information Report, which can be found on the HST Documents webpage (linked from the Cycle 26 Announcement webpage.) This document contains a discussion of the issues surrounding Large Program scheduling.

 Treasury Proposals should be identified in the "Special Proposal Types" section of the proposal. 

The Scientific Justification section of the proposal (see HST Cycle 26 Preparation of the PDF Attachment) should include a description of the scientific investigations that will be enabled by the final data products, and their importance. The Description of the Observations section of the proposal should not only describe the proposed observations and plans for data analysis, but should also describe the data products that will be made available to STScI and the community, the method of dissemination, and a realistic time line.

Detailed Program Management Plans are required with the budget submissions.

Calibration GO Proposals

Calibration GO proposals will not be accepted in Cycle 26.

Snapshot (SNAP) Proposals

Snapshot proposals will not be accepted in Cycle 26.

Archival Research (AR) Proposals

Observations that are no longer proprietary are available for analysis by interested scientists through direct retrieval from the HST Data Archive or from the Hubble Legacy Archive (HLA). The retrieval is free and does not involve financial support. The HST Archival Research (AR) Program can, however, provide financial support for the analysis of such data sets. AR Phase I proposals must outline a management plan for analyzing the data. Detailed budgets are due in Phase II only (as is the case for GO Proposals). Proposals for AR funding are considered at the same time, and by the same reviewers, as proposals for observing time, on the basis of scientific merit. 

Only U.S. Investigators are eligible for funding of Archival Research.

Regular AR Proposals

Regular AR proposals will not be accepted in Cycle 26.

Legacy AR Proposals

A Legacy AR Proposal is defined by the following characteristics:

• The project should perform a homogeneous analysis of a well-defined subset of data in the HST Archive.
• The main goal should be to provide a homogeneous set of calibrated data and/or ancillary data products to the scientific community.
• The results of the project should enable a variety of new and important types of scientific investigations.
• We also encourage the development of  software tools for dissemination to the community.

The main difference between a Regular and a Legacy AR Proposal is that the former aims at performing a specific scientific investigation, while the latter will also create data products and/or tools for the benefit of the community. While Legacy AR Proposals will be judged primarily on the basis of scientific merit, the importance and broad applicability of the products produced by the Legacy Proposal will be key features in judging the overall scientific merit of the proposal.

It is a strict requirement for Legacy AR Proposals that the proposed data products be created and distributed to the community in a timely manner. Data products should also be delivered to STScI in suitable digital formats, to allow dissemination via the HST Data Archive or related channels.

It is anticipated that Legacy AR Proposals will be larger in scope and requested funds than most Regular AR Proposals. While there is no lower limit on the requested amount of funding, it is expected that most Legacy AR Proposals will require at least $120,000, and possibly up to a few times this amount, to accomplish their goals. Commensurate with the expected scope, Legacy AR Proposals are allowed to be multi-year projects, although this is not a requirement. Multi-year projects will be funded on a yearly basis, with continued funding beyond the first year subject to a performance review. Legacy AR Proposals will be evaluated by the TAC (see Proposal Selection Procedures) in conjunction with Large and Treasury GO Proposals. Descriptions of past programs are available on the HST Descriptions of past programs are available on the HST Treasury, Archival Legacy and Large Programs webpage.

The Scientific Justification section of the proposal should include a description of the scientific investigations that will be enabled by the final data products, and their importance. The Analysis Plan section should describe the plans for data analysis, the data products that will be made available to STScI and the community, the method of dissemination, and a realistic timeline.

Legacy AR Proposals - Cloud Computation Studies

All non-proprietary data for current Hubble instruments (ACS, COS, STIS, WFC3, FGS), have been made available as part of the Amazon Web Services (AWS) public dataset program (aws.amazon.com/public-datasets/). Providing these data in close proximity to AWS faciliates new types of compute-intensive analyses that may have not previously been possible due to individual researcher or research group compute resources. Proposals to make use of this dataset should include the phrase ‘Cloud Exploration:' at the beginning of their proposal title and should include a line item in their budget for AWS costs (limit $10,000 USD).

Example use cases for leveraging this data could include: Large scale (re)analyses of data to measure proper motions, computationally-intensive tasks such as training machine learning classifiers, and live community-facing services.

Further reading:

• Link to HST data on AWS: https://registry.opendata.aws/hst/
• AWS machine learning services: aws.amazon.com/machine-learning/
• AWS spot computing: aws.amazon.com/ec2/spot/spot-and-science/
• Educational & research use cases: aws.amazon.com/government-education/research-and-technical-computing/

Calibration AR Proposals

Calibration Proposals may be submitted as AR Proposals. AR Proposals are appropriate in cases where the necessary data have already been taken, or for programs that do not require specific data but aim to develop specialized software for certain HST calibration and data reduction tasks. Examples of topics that have been addressed by Calibration Programs of the type discussed here are:

• Calibration of Lyman-alpha flat fields
• Creation of a coronagraphic PSF library for STIS/CCD
• Characterization of the spectroscopic PSF for STIS/CCD

For a complete description of the instrument calibration plans/accuracies, and for other potential topics, please see the Scientific Instruments webpage.

Users submitting Calibration Proposals must contact the appropriate instrument group (accessible via the STScI Helpdesk) to discuss their program prior to submission.

Theory Proposals

The opportunity exists under the HST Archival Research Program to obtain financial support for theoretical research. Research that is primarily theoretical can have a lasting benefit for current or future observational programs with HST, and it is appropriate to propose theory programs relevant to the HST mission. 

A Theory Proposal should address a topic that is of direct relevance to HST observational programs, and this relevance should be explained in the proposal. Funding of mission-specific research under the HST Theory Program will be favored over research that is appropriate for a general theory program (e.g., the NASA Science Mission Directorate Astrophysics Theory Program; ATP). The primary criterion for a Theory Proposal is that the results should enhance the value of HST observational programs through their broad interpretation (in the context of new models or theories) or by refining the knowledge needed to interpret specific observational results (a calculation of atomic cross sections may fall under the latter category). The results of the theoretical investigation should be made available to the community in a timely fashion. 

Theory proposals should describe the impact on observational investigations with HST. Review panels will consist of observational and theoretical astronomers with a broad range of scientific expertise. They will not necessarily have specialists in all areas of astrophysics, particularly theory, so the proposals must be written for general audiences of scientists. The ‘Analysis Plan’ section of the proposal should discuss the types of HST data that will benefit from the proposed investigation, and references to specific data sets in the HST Data Archive should be given where possible. This section should also describe how the results of the theoretical investigation will be made available to the astronomical community, and on what time-scale the results are expected.

As with the other AR Proposals, there is no limit to the funding that may be requested in Theory Proposals. However, with this solicitation we are seeking only Legacy Theory proposals, Regular Theory proposals will not be accepted in Cycle 26. It is expected that most Legacy Theory Proposals will require at least $120,000, and possibly up to a few times this amount, to accomplish their goals. Commensurate with the expected scope, Legacy Theory Proposals are allowed to be multi-year projects, although this is not a requirement. Multi-year projects will be funded on a yearly basis, with continued funding beyond the first year subject to a performance review. Legacy Theory Proposals will be evaluated by the TAC (see Proposal Selection Procedures) in conjunction with Large and Treasury GO Proposals. Descriptions of past programs are available on the HST Descriptions of past programs are available on the HST Treasury, Archival Legacy and Large Programs webpage.

The Scientific Justification section of the proposal should include a description of the scientific investigations that will be enabled by the final data products, and their importance. The Analysis Plan section should describe the plans for data analysis, the data products that will be made available to STScI and the community, the method of dissemination, and a realistic timeline.

Detailed Program Management Plans are required with the budget submissions.

Guidelines for AR Proposals

Please consider the following when developing your AR Proposal:

• In general, any HST data that you wish to analyze must reside (or be expected to reside) in the Archive, and be released from proprietary rights by the start of Cycle 26 (October 1, 2018).
• Users should consult the Large Searches and Requests webpage for information on searching for and downloading large datasets.
• Programs that require funding for Archival Research and also new observations should be submitted as two separate proposals: one requesting funding for the Archival Research, and the other proposing the new observations. The proposals should refer to each other so that the reviewers will be aware that the proposals are part of the same project.
• Investigators are allowed to submit an AR Proposal to analyze data that was obtained in a previous GO Program on which they were themselves PI or Co-I, but only if the goals of the AR Proposal differ significantly from those for which GO funding was awarded previously.
• STScI encourages the submission of AR Proposals that combine HST data with data from other space-missions or ground-based observatories, especially those data contained in the Mikulski Archive for Space Telescopes (MAST). STScI is an active partner of the Virtual Observatory (VO), and MAST is implementing VO technology to make its data holdings available. In particular, the MAST Data Discovery Portal is available at http://mast.stsci.edu/explore. The Discovery Portal is a one-stop Web interface to access data from all of the MAST supported missions, including HST (in particular the Hubble Legacy Archive- HLA, and Hubble Source Catalog- HSC), Kepler, GALEX, FUSE, IUE, EUVE, and Swift-UVOT.

Suggestions for AR Proposals

STScI would like to point out the following sources for Archival Research:

• The data being obtained for the Frontier Fields Program.
• The data obtained by the HST Pure Parallel Program.
• The data obtained for the Hubble Deep Field (HDF), the Hubble Deep Field-South (HDF-S) and the Hubble Ultra Deep Field (UDF).
• The data obtained by the HST Treasury Programs, which are described on the HST Treasury, Archival Legacy and Large Programs webpage. Community-contributed high-level science products from imaging and spectroscopic surveys (including GOODS, GRAPES, and GEMS) are available from the MAST High Level Science Product webpage.
• Projects that utilize the Hubble Source Catalog. A few potential examples are listed in the HST Primer.

Joint Observing Programs

STScI has reached agreements with several other observing facilities to award time for joint programs in which HST science is the prime science, but multi-wavelength observations from another ancillary observatory are critical for the science goals of the proposal. Joint programs may be for any amount of HST time, including Small Proposals of < 35 orbits.

Joint HST-Chandra Observing Proposals

If your science project requires observations from both HST and the Chandra X-ray Observatory, you can submit a single proposal to request time on both observatories to either the HST Cycle 26 or the Chandra Cycle 20 review. This avoids the “double jeopardy” of having to submit proposals to two separate reviews. A description of past HST joint programs is available on the HST Joint Programs webpage.

Joint HST-Chandra proposals are of two types:

Regular HST-Chandra Proposals: By agreement with the Chandra X-ray Center (CXC), STScI will be able to award up to 400 kiloseconds of Chandra observing time. Similarly the CXC will be able to award up to 100 orbits of HST time to highly rated proposals awarded Chandra time in its TAC process. The only criterion above and beyond the usual review criteria is that the project must be fundamentally of a multi-wavelength nature, and that both sets of data are required to meet the science goals. Time will only be awarded to joint proposals if both data sets are required for the proposed science. It is not essential that the project requires simultaneous Chandra and HST observations. Chandra time will only be awarded in conjunction with new HST observations (and should not be proposed for in conjunction with an AR or Theory Proposal).

Large HST-Chandra Proposals: By agreement with the CXC, STScI will be able to award an additional 600 kiloseconds of Chandra observing time for Large joint programs. These programs are defined as requiring at least 75 orbits of HST time and at least 400 ksec of Chandra observations. Similarly, CXC will be able to award up to 150 orbits for Large Programs submitted to the Chandra TAC. As with Regular HST-Chandra Proposals, the only criterion above and beyond the usual review criteria is that the project must be fundamentally of a multi-wavelength nature, and that both sets of data are required to meet the science goals. It is not essential that the project requires simultaneous Chandra and HST observations.

Of the 1 Msec of Chandra observing time that can be awarded in the HST review, only approximately 15% of the observations may be time-constrained. In addition, only one rapid ToO can be awarded (less than 20 days turn-around time). A Chandra ToO is defined as an interruption of a command load, which may include several predictable observations within that one-week load. HST Cycle 26 proposers should keep their Chandra requests within these limits.

Regular proposals for combined HST and Chandra observations should be submitted to the observatory that represents the prime science (not to both observatories). Large HST-Chandra proposals (or Very Large Programs, as CXC defines them) may be submitted to either, but not both, observatories. STScI reserves the right to disallow HST observations that duplicate those approved via any joint program unless the duplications are justified in the original proposals. The Chandra Cycle 20 deadline is March 15, 2018 at 6 pm EDT. While there is multi-wavelength expertise in the review panels for both observatories, typically the HST panels will be stronger in IR/optical/UV science and the Chandra panels in X-ray science.

Establishing the technical feasibility of the Chandra observations is the responsibility of the PI, who should review the Chandra documentation or consult with the CXC. A description of the technical information that should be included in the proposal is given in Joint HST-Chandra Observations. For proposals that are approved by HST, the CXC will perform detailed feasibility checks in Chandra Cycle 20. The CXC reserves the right to reject any previously HST-approved observation that proves infeasible, impossible to schedule, and/or dangerous to the Chandra instruments. Any Chandra observations that prove infeasible or impossible could jeopardize the overall science program and may cause revocation of the corresponding HST observations. Duplicate Chandra observations may also be rejected by the CXC.

Joint HST-Chandra Proposals must be identified in the ‘Special Proposal Types’ section of the proposal. Also, you must include technical information about the Chandra observations in the ‘Coordinated Observations’ section of the proposal.

Joint HST/XMM-Newton Observing Proposals

If your science project requires observations from both HST and the XMM-Newton Observatory, you can submit a single proposal to request time on both observatories to either the HST Cycle 26 or the XMM-Newton Cycle AO-18 review. Joint HST/XMM-Newton Proposals should be submitted to the observatory that represents the prime science facility (not to both observatories). A description of past HST joint programs is available on the HST Joint Programs webpage.

By agreement with the XMM-Newton Observatory, the HST TACs will be able to award up to 150 kiloseconds of XMM-Newton observing time. Similarly the XMM-Newton TACs will be able to award up to 30 orbits of HST time. The only criterion above and beyond the usual review criteria is that the project must be fundamentally of a multi-wavelength nature, and that both sets of data are required to meet the science goals. Time will only be awarded to joint proposals if both data sets are required for the proposed science. XMM-Newton time will only be awarded in conjunction with new HST observations (and should not be proposed for in conjunction with an AR or Theory Proposal). Proposers should take special care in justifying both the scientific and technical reasons for requesting time on both missions.

It is not essential that the project requires simultaneous XMM-Newton and HST observations. No XMM-Newton observations with a reaction time of less than five working days from the trigger date will be considered. Target of Opportunity (ToO) Proposals must state explicitly whether the HST observations require a disruptive ToO. No more than one disruptive ToO will be allocated per proposal. It is the responsibility of the PI to inform both observatories immediately if the trigger criterion is fulfilled.

Proposals for combined HST and XMM observations should be submitted to the observatory that represents the prime science (not to both observatories). STScI reserves the right to disallow HST observations that duplicate those approved via any joint program unless the duplications are justified in the original proposals. The XMM-Newton AO-18 deadline is nominally October 6, 2018. While there is multi-wavelength expertise in the review panels for both observatories, typically the HST panels will be stronger in IR/optical/UV science and the XMM panels in X-ray science.

Establishing the technical feasibility of the XMM-Newton observations is the responsibility of the PI, who should review the XMM-Newton Instrument Handbooks. A description of the technical information that should be included in the proposal is given in Joint HST-XMM Observations. All standard observing restrictions for both observatories apply to joint proposals. For proposals that are approved, both projects will perform detailed feasibility checks. Both projects reserve the right to reject any approved observation that is in conflict with safety or schedule constraints, or is otherwise deemed to be non-feasible.

Joint HST/XMM-Newton Proposals must be identified in the ‘Special Proposal Types’ section of the proposal. Also, you must include technical information about the XMM-Newton observations in the ‘Coordinated Observations’ section of the proposal.

Joint HST-NOAO Observing Proposals

By agreement with the National Optical Astronomy Observatory (NOAO), STScI will be able to award time on NOAO facilities to highly ranked proposals that request time on both HST and NOAO telescopes. The award of time on NOAO facilities will be subject to approval by the NOAO Director, after nominal review by the NOAO TAC to avoid duplication of programs. Joint HST/NOAO Proposals should be submitted to the observatory that represents the prime science facility (but not both). The important additional criterion for the award of NOAO time is that both the HST and the ground-based data are required to meet the science goals of the project. Time will only be awarded to joint proposals if both data sets are required for the proposed science. It is not essential that the project requires simultaneous NOAO and HST observations. Under this agreement, NOAO time will only be awarded in conjunction with new HST observations (and should not be proposed for in conjunction with an AR or Theory Proposal). Major results from these programs would be credited to NOAO and HST. A description of past HST joint programs is available on the HST Joint Programs webpage.

NOAO has offered up to 5% of its available time to proposals meeting the stated criteria. NOAO observing time will be implemented during the 2019B NOAO observing semester (for August 2019 to January 2020 observations). Time cannot be requested for the preceding semester, 2019A. Time may be requested only for those facilities listed on the NOAO/NASA Collaboration webpage. Under this agreement approximately 15-20 nights per telescope per year will be available on most (but not all) NOAO telescopes. Only a fraction of the time is available on some facilities - the WIYN and SMARTS telescopes - and so the 5% cap applies only to this fraction. In addition, time on heavily-subscribed resources may be limited by the NOAO Director.

Establishing the technical feasibility of the proposed NOAO observations is the responsibility of the PI, who should review the NOAO documentation or consult with NOAO directly. A description of the technical information that should be included in the proposal is given in Joint HST-NOAO Observations. If approved for NOAO time, the PI must submit, by the nominal March 30, 2019 deadline, an NOAO Phase II form giving detailed observing information appropriate to the particular NOAO telescope and instrument. In addition, for NOAO time on Gemini, successful PIs will be required to submit a complete NOAO proposal by the nominal March 30, 2019 deadline on the standard NOAO proposal form. This will be reviewed by the regular NOAO TAC.

NOAO will perform feasibility checks, and reserves the right to reject any approved observation determined to be infeasible, impossible to schedule, and/or dangerous to the telescopes or instruments. Any NOAO observations that prove infeasible or impossible could jeopardize the overall science program and may cause revocation of the corresponding HST time allocation.

Joint HST-NOAO Proposals must be identified in the ‘Special Proposal Types’ section of the proposal. Also, you must include technical information about the NOAO observations in the ‘Coordinated Observations’ section of the proposal.

Joint HST-NRAO Observing Proposals

By agreement with the National Radio Astronomy Observatory (NRAO), STScI will be able to award time on NRAO facilities to highly ranked proposals that request time on both HST and NRAO telescopes. NRAO has offered up to 3% of the available time on its North American facilities, namely the Robert C. Byrd Green Bank Telescope (GBT), the Very Large Array (VLA), and the Very Long Baseline Array (VLBA), for allocation by the HST TAC, subject to a maximum of 5% of the available time in any given array configuration. In return, STScI has offered 30 orbits of HST time for allocation by the NRAO TAC to proposals submitted on or before either of the two NRAO semester deadlines. These are nominally February 1, 2018 for semester 2018B, and August 1, 2018 for semester 2019A. Joint HST/NRAO Proposals should be submitted to the observatory that represents the prime science facility (not to both observatories). STScI reserves the right to disallow HST observations that duplicate those approved via any joint program unless the duplications are justified in the original proposals. A description of past HST joint programs is available on the HST Joint Programs webpage.

NRAO observing time awarded through the HST Cycle 26 review will be implemented during the 2018B and 2019A observing semesters. The award of time on NRAO facilities will be subject to approval by the NRAO Director, after nominal review by the NRAO TAC to avoid duplication of programs. The important additional criterion for the award of NRAO time is that both the HST and the radio data are required to meet the science goals of the project. Time will only be awarded to joint proposals if both data sets are required for the proposed science. It is not essential that the project requires simultaneous NRAO and HST observations. Under this agreement, NRAO time will only be awarded in conjunction with new HST observations (and should not be proposed for in conjunction with an AR or Theory Proposal). Major results from these programs would be credited to NRAO and HST.

Establishing the technical feasibility of the proposed radio observations is the responsibility of the PI, who should review the NRAO documentation or consult with NRAO directly. If approved for NRAO time, the PI must submit detailed observing information appropriate to the relevant NRAO facility. A description of the technical information that should be included in the proposal is given in Joint HST-NRAO Observations.

NRAO will perform a technical review of proposals approved by the HST TAC, and reserves the right to reject any approved observation determined to be infeasible, impossible to schedule, and/or dangerous to the telescopes or instruments. Any NRAO observations that prove infeasible or impossible could jeopardize the overall science program and may cause revocation of the corresponding HST time allocation. We therefore urge proposers to discuss technical concerns with appropriate staff at both observatories. Discussions with NRAO staff should occur via the NRAO helpdesk.

Proposers must always check whether appropriate archival data exist, and provide clear scientific and technical justification for any new observations of previously observed targets. Observations awarded time that duplicate observations already approved by HST or NRAO for the same time period may be canceled, or data sharing and cooperation among different groups may be necessary, as determined by the two observatories. This includes ToOs with similar trigger criteria, with or without previously known coordinates.

Be aware that some HST targets might not require new NRAO observations because the joint science goals can be met using non-proprietary archival data from the VLA, VLBA, or GBT that are available at http://science.nrao.edu/facilities/vla/archive. Also note that VLA continuum images from sky surveys at a wavelength of 20cm and at a FWHM resolution of 45 arc seconds (see http://www.cv.nrao.edu/nvss/) or 5 arc seconds (see http://sundog.stsci.edu/top.html) are available.

All scientific data from NRAO telescopes have a proprietary period where the data are reserved for the exclusive use of the observing team. The data archive policy and proprietary periods are given at
https://science.nrao.edu/observing/proposal-types/datapolicies

This policy applies to NRAO data taken through the joint HST-NRAO program.

Joint HST-NRAO Proposals must be identified in the ‘Special Proposal Types’ section of the proposal. Also, you must include technical information about the NRAO observations in the ‘Coordinated Observations’ section of the proposal.

Mid-Cycle GO Proposals

Up to 150 orbits per cycle will be available for Mid-Cycle GO programs in Cycle 26. Mid-Cycle programs provide the community with an opportunity to propose for in-cycle observations of recently-discovered, non-transient objects. As such, they complement Director’s Discretionary programs, which target unexpected transient phenomena and time-critical observations. Instructions and up-to-date information can be found on the Mid-cycle Proposal Submission Page.

Mid-Cycle GO Proposals must meet the following prime criteria:

• Proposers must provide a well-justified explanation of why the proposal could not have been submitted in response to the standard annual Call for Proposals: for example, the target source may have been identified subsequent to the most recent proposal deadline.
• Proposers must provide a clear description of the scientific urgency of these observations and why they should be executed in the present cycle.

Proposals should be submitted via the Astronomer’s Proposal Tool (APT) as type GO, using the Mid-Cycle template for the pdf attachment. Upon completion of your Mid-Cycle submission, your program will be transferred to the STScI for processing. If you run into problems submitting a Mid-Cycle Request, submit a question to http://hsthelp.stsci.edu for investigation/resolution.

Mid-Cycle proposals may be submitted at any time prior to January 30th, 2019. Proposals received by then will be considered for implementation in the April 1st, 2019 to September 30th, 2019 time-frame.

Proposals for Mid-Cycle time must be sufficiently detailed for adequate evaluation, comparable with proposals submitted for the regular observing cycles as described in the current Call for Proposals. Among other things,