10.3 ACS Solar Blind Channel, SBC

Observations with HST's ACS instrument can be done with the Solar Blind Channel (SBC), and the Astronomer’s Proposal Tool (APT) has parameters for specifying these observations.

Expand/Collapse all...

On This Page

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.


There is one detector on ACS that can be used to obtain ultraviolet data, and that is the SBC.

Mode = ACCUM Config = ACS/SBC

The SBC uses a MAMA detector which is a photon-counting device that provides a two-dimensional ultraviolet capability. The MAMA accumulates photons in the ACS data buffer as they are received, producing images with 1024 × 1024 pixels. For a more detailed description, see the discussion of SBC ACCUM mode in the ACS Instrument Handbook.

Aperture or FOV

The permitted apertures for this mode are SBC or SBC-FIX or SBC-LODARK. 

Note: that the prisms are not permitted when the Aperture is SBC-LODARK.

SBC must be specified if spectral element PR110L or PR130L is specified (STScI software will adjust the HST pointing to compensate for the refraction).

Spectral Element

See Table 10.7: Spectral Elements for use with the ACS/SBC Configuration.

Note: the prisms are not permitted when the Aperture is SBC-LODARK.


No wavelength should be specified for this mode.

Optional Parameters

There are no Optional Parameters in this Mode.

Unlike WFC, SBC exposures with a dispersing spectral element (PR110L or PR130L) will not have an additional image exposure scheduled automatically (see WFC ACCUM mode descriptions of optional parameter AUTOIMAGE). If an image exposure is desired in combination with a prism exposure, it must be entered as a separate exposure specification. It is best to place it immediately before or after the prism exposure in the same visit (see the ACS Instrument Handbook for more details).

A direct imaging exposure is required for the prism wavelength calibration. Note that its bright-object constraints will be more stringent than those of the prism exposure, so the least sensitive filter feasible is recommended.

Number of Iterations

Enter the number of times this Exposure Specification should be repeated.

Time Per Exposure

Enter the exposure time to apply to each iteration.

Note that Time_per_Exposure for individual SBC exposures must be an integer multiple of 0.1 second and must be in the range of 0.1 to 3600 sec.

Special Requirements

For restricted parameters


Expand/Collapse all...

Related Links

10.2 ACS Wide Field Channel, WFC

Table of Contents

Change Log