11.5.2 COS Spectral Elements and Central Wavelengths

This article lists the legal COS spectral element/wavelength combinations for the COS/FUV and COS/NUV configurations.

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Format definitions

Boldface type indicates the name of an APT parameter or a value for a parameter.

(red star) Black text indicates an important note.

Magenta text indicates available but unsupported parameters (requires prior approval from STScI).

Red text indicates restricted parameters (for STScI use only).

Brown text indicates text file parameters.

Items in brackets - <value> - are required values.

Items in square brackets - [<value>] - are optional.

The  following  table  specifies  the  legal  COS  spectral  element/wavelength combinations for the COS/FUV and COS/NUV configurations. For information on the Lifetime Positions used for each central wavelength see Table 11.1 Supported settings for FUV ACCUM and TIME-TAG exposures):

Table 11.5: COS Spectral Elements and Central Wavelengths

Configuration

Spectral Element

Central Wavelengths (Angstroms)

COS/FUV

G130M

10551, 10961, 12221,

1291, 1300, 1309, 1318, 1327

G140L

8001, 1105, 1230, 1280

G160M

15331, 1577, 1589, 1600, 1611, 1623

COS/NUV2

G185M

1786, 1817, 1835, 1850, 1864, 1882, 1890, 1900, 1913,

1921, 1941,1953, 1971, 1986, 2010

G225M

2186, 2217, 2233, 2250, 2268, 2283, 2306, 2325, 2339,

2357, 2373, 2390, 2410

G230L

2635, 2950, 3000, 3360

G285M

2617, 2637, 2657, 2676, 2695, 2709, 2719, 2739, 2850,

2952, 2979, 2996, 3018, 3035, 3057, 3074, 3094

MIRRORA3

N/A

MIRRORB4

N/A

1Target acquisition modes are not allowed with this central wavelength.

2Due to increased COS NUV detector background and mechanism position uncertainties, certain central wavelength settings have proven to be unreliable in the NUV ACQ/PEAKXD target acquisition phase. The central wavelengths settings that appear in bold are the preferred central wavelengths for STRIPE=DEF NUV ACQ/PEAKXD exposure. See the COS Instrument Handbook and Mode = ACQ/PEAKD Config = COS/NUV  for more details.

3The MIRRORA spectral element positions a flat mirror in the beam to produce an image of the sky with a field of view slightly larger than the diameter of the aperture. If you intend to produce an image and there are no special bright object concerns, MIRRORA should be used. Restricted for wavecals and forbidden for flats.

4MIRRORB uses the same mirror which has an order-blocking filter in front of it, so that the light is reflected off the front surface of the filter rather than the mirror itself. MIRRORB attenuates the image and is suitable for use with bright objects. Restricted for wavecals and forbidden for flats.


For available but unsupported Configurations at non default lifetime positions

Table 11.6: Additional configurations offered in AVAILABLE mode.

(Note that while these G130M/LP3 combinations and G160M/1533 are AVAILABLE for TIME-TAG and ACCUM modes, they are not AVAILABLE for spectroscopic ACQs.)

Spectral Element

Central Wavelength (A)

LIFETIME-POS

Available for ACQs?

SEGMENT (DEFAULT)

FP-POS

G130M

1291

LP3

No

A, B, BOTH

1, 2, 3, 4, ALL

G130M

1300

LP3

No

A, B, BOTH

1, 2, 3, 4, ALL

G130M

1309

LP3

No

A, B, BOTH

1, 2, 3, 4, ALL

G130M

1318

LP3

No

A, B, BOTH

1, 2, 3, 4, ALL

G130M

1327

LP3

No

A, B, BOTH

1, 2, 3, 4, ALL

G160M1533LP4NoA, B, BOTH1, 2, 3, 4, ALL
G160M1577LP4YesA, B, BOTH1, 2, 3, 4, ALL
G160M1589LP4YesA, B, BOTH1, 2, 3, 4, ALL
G160M1600LP4YesA, B, BOTH1, 2, 3, 4, ALL
G160M1611LP4YesA, B, BOTH1, 2, 3, 4, ALL
G160M1623LP4YesA, B, BOTH1, 2, 3, 4, ALL



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Change Log

Version Cycle 31 June 2023

       Removed old PR link from Change Log.

Version Cycle 30 April 2022

       PROPINST-91380 Document COS FUV Lifetime Position 6

Version Cycle 29 May 2021

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Version Cycle 29 April 2021

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Version Cycle 26 October 2018

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    11.5.2 COS Spectral Elements and Central Wavelengths
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    11.5.2 COS Spectral Elements and Central Wavelengths

Initial Conversion from the HST Cycle 25 Phase II Proposal Instructions (Engineering) Version Cycle 25 (June 2018)