MONS Field Monitor Requirements Specification and Parallel Science
MONS Field Monitor Requirements Specification and Parallel Science
Rømer System Definition Phase 2000/2001
Document no.: MONS/IFA/PL/RS/0002(1)
Date: 22.04.2001
Prepared by: Hans Kjeldsen, Tim Bedding and Chris Boshuizen
Checked by: Jørgen Christensen-Dalsgaard
Authorized by: Jørgen Christensen-Dalsgaard
Classification: Open: The document is unclassified and there are no
restrictions in circulation.
MONS Field Monitor
Requirements Specification
and Parallel Science
ãTeoretisk Astrofysik Center, Institut for Fysik og Astronomi, Aarhus Universitet
This document may only be reproduced with permission of TAC/IFA, except within the Rømer project where any type of reproduction is allowed.
A draft issue of parts of this document exist in the following document: MONS/MFM/SPEC/2001/001
DISTRIBUTION
This document is for internal use by the Rømer project. All Rømer key persons will be able to access the document via the DSRI webpage: http://www.dsri.dk/roemer/pro.
Contents
1. Scope 5
2. Applicable Documents 6
3. The MONS Field Monitor requirements 7
3.1 Assumed optics 7
3.2 Assumed detector 7
3.3 Required stability of focal plane 8
3.4 Assumed read-out electronics 8
3.5 Required readout modes 8
Mode-1: 8
Mode-2: 10
Mode-3: 11
Mode-4: 12
Mode-5: 13
Mode-6: 14
3.6 Memory requirements 15
3.6.1 Summary of memory requirements: 18
4. MONS Field Monitor Parallel Science Programme 19
4.1 Variability throughout the HR-diagram 22
5.2 Planetary transits 22
5.3 Supernovae 25
5.4 Photometric variability of QSOs 26
5.5 Asteroids 26
1. Scope
This document specifies the requirements for the MONS Field Monitor on the Rømer satellite and discusses some potential parallel science programmes. The document has been prepared by the Theoretical Astrophysics Center and the Institute of Physics and Astronomy at Aarhus University as a contribution to the Rømer System Definition Phase (The Danish Small Satellite Programme).
2. Applicable Documents
AD1: Rømer Science Mission Specification
MONS/IFA/MIS/RS/0001(1)
AD2: MONS Payload Requirements Specification
MONS/IFA/PL/RS/0001(2)
AD3: Requirements for the Star Tracker Parallel Science Programme
MONS/IFA/PL/RS/0003(1)
AD4: MONS Payload Electronics Requirement Specification
TERMA # 255503 DT
AD5: MONS Field Monitor System Definition Phase Design Report
MONS/AUS/PL/RP/0002(1)
3. The MONS Field Monitor requirements
The purpose of the MONS Field Monitor (MONS FM) is to monitor the field of view (FOV) of the MONS Telescope and its immediate surroundings for faint variable stars, which could impair the observations of the bright target star. The MONS Telescope FOV is determined by the size of the in-focus field stop, whose diameter is about 11 arcmin. The dynamic range of the MONS FM should be 7-8 magnitudes.
As specified in AD2, we require that any variability in a neighbouring star which produces a peak in the final MONS Telescope amplitude spectrum more than 2.5 times the noise level should be detected at the 4-sigma level by the MONS FM. For example, if the target has magnitude V=3 then a neighbouring star at V=10.5 (1000 times fainter) must be measured to a precision which gives a noise level of 600 ppm (0.06%) in the amplitude spectrum.
Achieving this requires differential photometry of the field using in-focus imaging. The baseline is to use the lens barrel from the Integral OMC (Optical Monitoring Camera). The detector will be a TERMA Star Tracker equipped with a 12-bit A/D Converter.
3.1 Assumed optics
Optical system: / The Integral OMC opticsField of view: / 5 deg x 5 deg
Aperture: / 50 mm diameter
Focal length: / 153.7 mm (f/3.1)
Optical throughput: / > 70 % at 550 nm
PSF: / > 70 % of energy within 1 pixel
Angular pixel size: / 17.6 x 17.6 arcsec
Table Properties of the Integral OMC optics.
To avoid saturating the target star, it may be desirable to use a filter. If so, the passband should be in the blue, since this is where the amplitudes of pulsating stars are greatest. The baseline is to use a filter with passband 400-435 nm and 80% peak transmission. The filter only needs to cover the central region (40 arcmin), to cover the MONS Telescope field of view, and it would be desirable to restrict the size of the filter to this value or slightly larger because that would allow the rest of the MONS FM field to be used unfiltered for parallel science.
3.2 Assumed detector
CCD chip: / Marconi Applied TechnologiesCCD 47-20 Back thinned (AIMO CCD Sensor)
Image format: / 1024 x 1024 pixels
Image Area Size: / 13.3 x 13.3 mm2
Frame transfer Operation: / 1024 x 1024 pixels Storage area
Pixel Size: / 13 mm square
CCD Operating Temperature: / – 10 ˚C
CCD Temperature Stability: / 5 ˚C (RMS)
CCD Temperature Measurement
Accuracy (Telemetry): / 1 ˚C (RMS)
Table The specifications for the MONS FM detector.
3.3 Required stability of focal plane
Distance between optics and CCD should ensure that the PSF < 1.25 pixels. This means stability to ±15 μm.
3.4 Assumed read-out electronics
Saturation Level: / 35,000 e/pixelsA/D-Conversion: / 12 bits or better
Conversion factor: / 10 e/ADU
Readout Frequency / 1 MHz
Readout noise: / 20 e/pixel
Integration Time: / 10 ms to 2 s (programmable)
Integration time accuracy / 1 μs (RMS)
Read-out Modes: / Full frame and window read-out
Read-out time: / 1 μs/pixel (1 MHz)
Vertical shift time: / 6 μs (166 kHz)
150 μs for first vertical shift
100 μs during readout
Horizontal shift time: / 380 ns (2.6 MHz)
Examples of readout times: / 15 x 15 pixels: / 14 ms
50 x 50 pixels: / 32 ms
100 x 100 pixels: / 61 ms
200 x 200 pixels: / 128 ms
200 x 200 + 20x15x15 pixels: / 276 ms
1024 x 1024 pixels: / 1151 ms
Table The specifications for the MONS FM read out electronics.
3.5 Required readout modes
Below we describe the 6 different readout modes that we plan to execute on the MONS Field Monitor. The different modes are described during a 20 sec activity cycle:
· Mode-1: -0.2 < V < 0.6
· Mode-2: 0.6 < V < 1.3
· Mode-3: 1.3 < V < 2.1
· Mode-4: 2.1 < V < 3.0
· Mode-5 3.0 < V < 4.6
· Mode-6: V > 4.6
Mode-1:
V < 0.6: 20 sec activity cycle:
No activity: 4 msec
4 x transfer: 28 msec
Execute 18 times: 10800 msec
Execute 10 times: 210 msec
14 msec exp (15x15)
Saturation in 35nm filter area: V=-0.2
7 msec transfer
End execute
Execute 9 times: 351 msec
32 msec exp (50x50)
Saturation in 35nm filter area: V=0.6
7 msec transfer
End execute
32 msec exp (15x15) 32 msec
Saturation in 35nm filter area: V=0.6
7 msec transfer 7 msec
End execute
Execute 12 times: 468 msec
32 msec exp (50x50)
Saturation in 35nm filter area: V=0.6
7 msec transfer
End execute
Execute 6 times: 7542 msec
1250 msec exp (1024x1024)
Saturation in 35nm filter area: V=4.6
Saturation in NO filter area: V=7.5
7 msec transfer
End execute
1151 msec readout 1151 msec
7 msec transfer 7 msec
Total: 20000 msec
Figure 3.5.1: The scatter per 20 sec exposure sequence for the MONS Field Monitor operated in readout mode 1. The two curves represent scatter for differential photometry. The central field is covered by a 35 nm wide blue filter.
Mode-2:
0.6 < V < 1.3: 20 sec activity cycle:
8 x transfer: 56 msec
Execute 10 times: 10700 msec
Execute 10 times: 390 msec
32 msec exp (50x50)
Saturation in 35nm filter area: V=0.6
7 msec transfer
End execute
Execute 9 times: 612 msec
61 msec exp (100x100)
Saturation in 35nm filter area: V=1.3
7 msec transfer
End execute
61 msec exp (50x50) 61 msec
Saturation in 35nm filter area: V=1.3
7 msec transfer 7 msec
End execute
Execute 8 times: 544 msec
61 msec exp (100x100)
Saturation in 35nm filter area: V=1.3
7 msec transfer
End execute
Execute 6 times: 7542 msec
1250 msec exp (1024x1024)
Saturation in 35nm filter area: V=4.6
Saturation in NO filter area: V=7.5
7 msec transfer
End execute
1151 msec readout 1151 msec
7 msec transfer 7 msec
Total: 20000 msec
Figure 3.5.2: Same as Figure 3.5.1, but for readout mode 2.
Mode-3:
1.3 < V < 2.1: 20 sec activity cycle:
No activity: 5 msec
7 msec transfer: 7 msec
Execute 166 times: 11288 msec
61 msec exp (100x100)
Saturation in 35nm filter area: V=1.3
7 msec transfer
End execute
Execute 6 times: 7542 msec
1250 msec exp (1024x1024)
Saturation in 35nm filter area: V=4.6
Saturation in NO filter area: V=7.5
7 msec transfer
End execute
1151 msec readout 1151 msec
7 msec transfer 7 msec
Total: 20000 msec
Figure 3.5.3: Same as Figure 3.5.1, but for readout mode 3.
Mode-4:
2.1 < V < 3.0: 20 sec activity cycle:
No activity: 5 msec
7 msec transfer: 7 msec
Execute 83 times: 11288 msec
129 msec exp (200x200)
Saturation in 35nm filter area: V=2.1
7 msec transfer
End execute
Execute 6 times: 7542 msec
1250 msec exp (1024x1024)
Saturation in 35nm filter area: V=4.6
Saturation in NO filter area: V=7.5
7 msec transfer
End execute
1151 msec readout 1151 msec
7 msec transfer 7 msec
Total: 20000 msec
Figure 3.5.4: Same as Figure 3.5.1, but for readout mode 4.
Mode-5:
3.0 < V < 4.6: 20 sec activity cycle:
No activity: 1 msec
4 x transfer: 28 msec
Execute 39 times: 11271 msec
282 msec exp (200x200 + 20 x 15 x 15)
Saturation in 35nm filter area: V=3.0
Saturation in NO filter area: V=5.9
7 msec transfer
End execute
Execute 6 times: 7542 msec
1250 msec exp (1024x1024)
Saturation in 35nm filter area: V=4.6
Saturation in NO filter area: V=7.5
7 msec transfer
End execute
1151 msec readout 1151 msec
7 msec transfer 7 msec
Total: 20000 msec
Figure 3.5.5: Same as Figure 3.5.1, but for readout mode 5.
Mode-6:
V > 4.6: 20 sec activity cycle:
Execute 16 times: 16 x 1250 msec
1243 msec exp (1024x1024)
Saturation in 35nm filter area: V=4.6
Saturation in NO filter area: V=7.5
7 msec transfer
End execute
Total: 20000 msec
Figure 3.5.6: Same as Figure 3.5.1, but for readout mode 6.
3.6 Memory requirements
For parallel science purposes, we will create a median-filtered image to be transmitted to the ground after each orbit. To do this, we expect to operate the MONS FM in the following mode (we only consider mode-6, which is the most critical mode concerning use of memory):
20-sec sequence:
Mem07: 341 x 341 pix with Mem07(x,y)==0 (233 kB - 16-bit)
Read-out #1: 1024 x 1024 12-bit frame:
Store central 200 x 200 in Mem01 (80 kB - 16-bit)
Execute Photometry on Mem01
20 stars near centre (XPOS, YPOS, SKY, FLUX, DIFF)
100 REALS (32-bit) - 0.4 kbyte
Store Full frame as 3x3 pix binning during
readout: 341 x 341 pix in Mem02 (233 kB - 16-bit)
Correct for pitch, yaw and roll: Mem02 --> Mem03
Read-out #2: 1024 x 1024 12-bit frame:
Store central 200 x 200 in Mem01 (80 kB - 16-bit)
Execute Photometry on Mem01
20 stars near centre (XPOS, YPOS, SKY, FLUX, DIFF)
100 REALS (32-bit) - 0.4 kbyte
Store Full frame as 3x3 pix binning during
readout: 341 x 341 pix in Mem02 (233 kB - 16-bit)
Correct for pitch, yaw and roll: Mem02 --> Mem04
Read-out #3: 1024 x 1024 12-bit frame:
Store central 200 x 200 in Mem01 (80 kB - 16-bit)
Execute Photometry on Mem01
20 stars near centre (XPOS, YPOS, SKY, FLUX, DIFF)
100 REALS (32-bit) - 0.4 kbyte
Store Full frame as 3x3 pix binning during
readout: 341 x 341 pix in Mem02 (233 kB - 16-bit)
Correct for pitch, yaw and roll: Mem02 --> Mem05
Read-out #4: 1024 x 1024 12-bit frame:
Store central 200 x 200 in Mem01 (80 kB - 16-bit)
Execute Photometry on Mem01
20 stars near centre (XPOS, YPOS, SKY, FLUX, DIFF)
100 REALS (32-bit) - 0.4 kbyte
Store Full frame as 3x3 pix binning during
readout: 341 x 341 pix in Mem02 (233 kB - 16-bit)
Correct for pitch, yaw and roll: Mem02 --> Mem06
do for x = 1 --> 341
do for y = 1 --> 341
sort Mem03, Mem04, Mem05, Mem06 so:
MemXX(x,y) =< MemYY(x,y) =< MemZZ(x,y) =< MemVV(x,y)
Mem07(x,y) = Mem07(x,y) +MemYY(x,y)+MemZZ(x,y)
enddo
enddo
Read-out #5: 1024 x 1024 12-bit frame:
Store central 200 x 200 in Mem01 (80 kB - 16-bit)
Execute Photometry on Mem01
20 stars near centre (XPOS, YPOS, SKY, FLUX, DIFF)
100 REALS (32-bit) - 0.4 kbyte
Store Full frame as 3x3 pix binning during
readout: 341 x 341 pix in Mem02 (233 kB - 16-bit)
Correct for pitch, yaw and roll: Mem02 --> Mem03
Read-out #6: 1024 x 1024 12-bit frame:
Store central 200 x 200 in Mem01 (80 kB - 16-bit)
Execute Photometry on Mem01
20 stars near centre (XPOS, YPOS, SKY, FLUX, DIFF)
100 REALS (32-bit) - 0.4 kbyte
Store Full frame as 3x3 pix binning during
readout: 341 x 341 pix in Mem02 (233 kB - 16-bit)
Correct for pitch, yaw and roll: Mem02 --> Mem04
Read-out #7: 1024 x 1024 12-bit frame:
Store central 200 x 200 in Mem01 (80 kB - 16-bit)
Execute Photometry on Mem01
20 stars near centre (XPOS, YPOS, SKY, FLUX, DIFF)
100 REALS (32-bit) - 0.4 kbyte
Store Full frame as 3x3 pix binning during
readout: 341 x 341 pix in Mem02 (233 kB - 16-bit)
Correct for pitch, yaw and roll: Mem02 --> Mem05
Read-out #8: 1024 x 1024 12-bit frame:
Store central 200 x 200 in Mem01 (80 kB - 16-bit)
Execute Photometry on Mem01
20 stars near centre (XPOS, YPOS, SKY, FLUX, DIFF)
100 REALS (32-bit) - 0.4 kbyte
Store Full frame as 3x3 pix binning during
readout: 341 x 341 pix in Mem02 (233 kB - 16-bit)
Correct for pitch, yaw and roll: Mem02 --> Mem06
do for x = 1 --> 341
do for y = 1 --> 341
sort Mem03, Mem04, Mem05, Mem06 so:
MemXX(x,y) =< MemYY(x,y) =< MemZZ(x,y) =< MemVV(x,y)
Mem07(x,y) = Mem07(x,y) +MemYY(x,y)+MemZZ(x,y)
enddo
enddo
Read-out #9: 1024 x 1024 12-bit frame: