| CAID: MIPS-250 | Title: Cosmic-ray limits on integration times: Si:As | |
| System: MIPS | Principal: dlp | Deputy: sstolovy |
| Objective: | To determine the maximum useful MIPS integration times in the presence of cosmic-ray hits for the 24um array. |
| Description: | While illuminating the detectors at a low level with the stimulators (or a reasonably faint zodiacal/cirrus background), take images at many different integration times up to the maximum allowed value to evaluate the trade off between "background limited" and "not completely swamped with particle hits." For example, this could be accomplished by executing a series of photometry AOTs over a range of integration times from 3 to 60 seconds. E.g., 3, 10, 30, and 60 seconds (only up to 30 seconds for 160um). This activity can be broken into three parts to facilitate scheduling prior to final telescope cooldown. The Ge:Ga arrays done now in MIPS-251. |
| Day: 61.5229166666686 | Suggested Order: O400 | ||
| Must be preceded by these activities (list by CAID): MIPS-245, MIPS-246 | |||
| Place in Schedule: For 24um, the backgrd radiance must be less than 1.0E-11 W/cm2/sr (< 30K). For 70um, the backgrd radiance must be less than 1.0E-12 W/cm2/sr (< 12 K). For 160um, the backgrd radiance must be less than 5.4E-13 W/cm2/sr (< 6 K). | |||
| Priority: Necessary | |||
Conditions | |||
| Maximum telescope temperature: | 6.5 K | ||
| Minimum telescope temperature: | 5.5 K | ||
| Should activity be repeated if focus changes? | No Repeat if focus changes by 0 mm | ||
| Maximum absolute pointing uncertainty: | 10 arcsec (1 sigma radial) | ||
| Maximum precision offset uncertainty: | 1 arcsec (1 sigma radial) | ||
| Observatory configuration: | standard | ||
| Go/No Go criteria: | Solar activity at a | ||
Duration: 80 minutes
| | Real time downlink:
No | | |||
| Data Volume (uncompressed): 115 Mbits | |||
| List Blocks, AORs, SERs, IERs, or unique sequences required (uplink): Can use photometry AORs for integration times up to 30 seconds on 24um array and 10 seconds on Ge:Ga arrays. Modified AORs will be required for the longest exposure times. Special data analysis | |||
| List Analysis tools required (downlink): Standard MIPS pipeline, image analysis package with statistical tools | |||
| Estimate of data turn around: 5 hours | |||
| Description: SUR data for each MIPS array will be analyzed to determine contribution to the noise from radhits. | |||
| Can proceed in parallel with other activity: Yes | |||
| Must outcome be confirmed before next activity: No | |||
| Method of Confirmation: Data analysis | |||
| Success criteria: Data is obtained and downlinked. Solar activity must be unremarkable during this task. | |||
| Contingency plan: Acquire required data through normal operations. This is a test of conditions external to SIRTF and cannot fail. | |||
Comments | |||
| References: | |||
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Additional Comments:
CTA temperature must be low enough that stray light is much lower (20 %) than the background sky level in each band. Boresite pointed to batch of sky without bright sources. Pointing accuracy is not at all critical (better than a few arcminutes is fine), but sources shouldn't be drifting across the array and so stability should be better than 1" (about 1/2 a 24um pixel) over 60 seconds.It may be possible to split this test into parts executed at different times based on telescope temperature. Location of MIPS apertures must be completed. Basic instrument commanding and functionality must have been confirmed.Related: Low-background data taken at different integration times to exercise the system. | |||
| This activity last updated: 4/19/2002 10:46:23 AM | |||