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We are writing to let you know that we will be supporting the planning of your Chandra HETGS observation(s).
Some changes to the Chandra instruments since launch as well as experience with flight data suggest that all HETGS instrument configurations should be re-examined and possibly changed slightly in order to enhance the observations' scientific value. The page http://space.mit.edu/ASC/calib/hetg_GO_info.html summarizes some of the most important changes you may wish to consider.
We want to make sure that the best science is obtained with the Chandra HETGS. Please take a look at the attachment and contact us about specific observation parameters and any adjustments you want to make. Your HETGS observation parameters, as they now appear in our observation data base (OBSCAT) can be viewed starting on the web at
http://cxc.harvard.edu/targets/
As appropriate, you will also find links so you may see the the HETGS orientation for the roll angle that would be used given the placement of the observation in the long term schedule. For further information about the instrument status and calibration you may want to consult the following web sites:
http://cxc.harvard.edu/, which includes these links in particular:
Attachment #2 to this e-mail is a list of AO2 HETG observations and a contact scientist to support the planning for each observation.
If Schulz is your contact scientist, use the contact priority:
In the mean time if you have any questions or thoughts please feel free to contact us. If everything is correct, please let us know that you are satisfied with the current set-up. (Please also email a copy of all correspondance to the Chandra Uplink Support archive at cus@head-cfa.harvard.edu.)
Sincerely,
Norbert S. Schulz
Herman L. Marshall
HETGS Chandra Planning Support Scientists
- - - Attachment #1 :
If your target is in the long term schedule information is needed by 7 weeks in advance. The target will not be scheduled earlier, but could be scheduled later, if necessary, due to other demands on the scheduling process. Note that all time and roll constraints will be honored. If your target is in in a "pool", it means it is in a pool of observations which have no constraints and are visible any time. These are used to fill in the weekly schedules to increase observing efficiency. Because these can be scheduled at any time, we request review of the configuration as soon as possible, so that we might use them. (We regret that it is inevitable that some of these will not be done until almost the very end of the observing cycle).
Events leading up to your observation are summarized briefly here:
See http://space.mit.edu/ASC/calib/hetg_GO_info.html for a discussion of issues relating to setting up observations and http://space.mit.edu/ASC/calib/hetgcal.html for HETGS calibration updates.
PARAMETER CROSS REFERENCE LIST
The following is a list of the key parameters which may be considered in optimizing an HETGS observation with reference to specific issues described in detail above.
| SI Mode | - This code for ACIS is determined by the ACIS parameters selected and may be identical to previously used ACIS SI Modes. This code is not set directly by users. |
| Offset Y | - Used to offset point along the dispersion direction to fine tune chip-gap locations, for example. We generally recommend moving +0.33 arcmin to avoid placing 0th order on a node boundary. |
| Offset Z | - generally preferable to use "Z-Sim" instead of "Offset Z". An offset in Z may be needed if the desired SIM aimpoint cannot be reached due to fid light conflict, which occurs for Z-SIM offsets of -11 to -8 mm. |
| Z-Sim | - Useful to move aim point on ACIS-S array closer to framestore area to reduce FI CTI effects. The nominal move is -3 mm but one may move more if the low energies of the dispersed HEG spectrum may be sacrificed. For a -3 mm shift, a 747 row subarray can be used without losing source events. |
| ACIS Exposure Mode | - TE or CC -- using CC mode increases timing resolution but data analysis can be difficult as the MEG and HEG events are not readily discerned. |
| Event TM Format | - For telemetry reasons, generally recommend "Faint" instead of "Very Faint"; "Graded" should be used only if the count rate is very high. |
| Frame Time | - Generally 3.2 sec for HETGS; may be reduced for pileup reduction if subarrays or CC mode are used. Ignored unless a longer exposure is desired than the minimum allowed for a given subarray. For a 747 row subarray, the frame time is 2.5 s. |
| Standard Chips | - "Y" for ACIS-S array operation. |
| I0 - I3 | - Ignored if "Standard Chips" is set to "Y". If "N", then specify the desired chips. ACIS-I chips may be combined with ACIS-S chips up to a total of 6. |
| S0 - S5 | - see I0 - I3 |
| Subarry Type | - Generally "None" for HETGS observations. If a Z-SIM shift of 3 mm is used, one may request a "CUSTOM" subarray of 747 rows starting at row 1. Other custom subarrays may be constructed with potential loss of dispersed events. |
| Duty Cycle Number Tprimary Tsecondary | - For use in Alternating Frame mode. This mode must be selected and used with care. The main objective is to reduce pileup in 0th order for a small fraction (usually < 5%) of the observation. |
| Event Filter Lower Range | - Events may be vetoed from the telemetry based on energy. This may be useful for telemetry reduction when, for example, sources are cut off at low energies due to the ISM. |
| Window Filter Start Row Start Column Height Width Lower Energy Energy Range Sample Rate | - Spatial window parameters may be useful for reducing telemetry rate on a bright source; note that "sample rate" allows some events to be telemtered, e.g., from zero-order region. It is generally recommended that *some* events from zeroth order be retained to facilitate data analysis and so that instrument problems may be diagnosed more easily on the ground. |
SeqNbr ObsId Target ExpTime PI Observer Contact ______ ____ ______________ ___ ___________ ____________ ________ 200075 599 Iota_Orionis 50 Canizares Schulz Schulz 200076 601 TY_Pyx 50 Canizares Huenemoerder Schulz 200081 974 Beta_Ceti 88 Linsky Gagne Marshall 200113 1885 EV_Lac 100 Osten - Marshall 200115 1887 ER_Vul 120 Brown - Marshall 200116 1888 HD_206267 40 Schulz - Schulz 200117 1889 HD_206267 40 Schulz - Schulz 200118 1890 HD_93497 80 Ayres - Schulz 200119 1891 HD_111812 140 Ayres - Schulz 200120 1892 HD_223460 100 Ayres - Schulz 200122 1894 Xi_UMa 80 Drake - Marshall 200123 1895 Gamma_Cas 54 Smith Evans Schulz 300046 1898 AO_Psc 100 Hellier - Marshall 300049 1901 V603_Aquilae 70 Mukai - Marshall 300052 1904 CH_Cyg 50 Wheatley - Marshall 390002 1010 Capella 30 Calibration Calibration Schulz 390006 1014 PKS2155-304 30 Calibration Calibration Marshall 400094 1016 Cyg_X-2 15 Canizares Schulz Schulz 400095 1017 EXO_0748-676 50 Canizares Schulz Schulz 400096 1018 4U_0142+61 25 Canizares Schulz Schulz 400097 1019 SS_433 25 Canizares Marshall Marshall 400098 1020 SS_433 25 Canizares Marshall Marshall 400099 1021 NGC6624 10 Murray Grindlay Schulz 400100 1022 NGC6624 10 Murray Grindlay Schulz 400118 1905 Cir_X-1 8 Brandt - Schulz 400119 1906 Cir_X-1 8 Brandt - Schulz 400120 1907 Cir_X-1 8 Brandt - Schulz 400122 1909 2S0921-630 80 Kallman - Schulz 400123 1910 1E1740.7-2942 70 Cui - Schulz 400133 1920 GRO_J1655-40 40 Liedahl - Schulz 400134 1921 GX340+0 25 Robba DiSalvo Schulz 400135 1922 GX340+0 5 Robba DiSalvo Schulz 400136 1923 4U1705-44 25 Robba DiSalvo Schulz 400137 1924 4U1705-44 5 Robba DiSalvo Schulz 400139 1926 Vela_X-1 85 Kahn Sako Schulz 400140 1927 Vela_X-1 30 Kahn Sako Schulz 400141 1928 Vela_X-1 35 Kahn Sako Schulz 400149 1936 XTE_J1748-288 30 Lee - Schulz 400150 1937 XTE_J1748-288 40 Lee - Schulz 400151 1938 XTE_J1748-288 70 Lee - Schulz 400152 1939 4U_1636-53 30 Schulz - Schulz 400153 1940 SS_433 20 Namiki Kawai Marshall 400154 1941 SS_433 20 Namiki Kawai Marshall 400155 1942 SS_433 20 Namiki Kawai Marshall 400156 1943 CEN_X-3 50 Wojdowski - Schulz 400157 1944 GRS_1915+105 30 Remillard - Schulz 400158 1945 GRS_1915+105 30 Remillard - Schulz 400159 1946 GRS_1915+105 30 Remillard - Schulz 400160 1947 OAO_1657-415 5 Chakrabarty - Schulz 500100 1034 RX_J0852.0-4622 31 Garmire Pavlov Schulz 500101 1035 RX_J0852.0-4622 0 Garmire Pavlov Schulz 500111 1045 N103B 120 Canizares Flanagan Schulz 500112 1046 Cas_A 70 Canizares Flanagan Schulz 600117 1560 NGC4696 95 Canizares Wise Marshall 700213 1597 Mkn_766 90 Canizares Ogle Marshall 700214 1598 NGC_5506 90 Canizares Ogle Marshall 700215 1599 H_1821+643 100 Canizares Ogle Marshall 700216 1600 Centaurus_A 50 Murray Kraft Marshall 700217 1601 Centaurus_A 50 Murray Kraft Marshall 700270 2080 NGC_3516 200 Turner - Marshall 700277 2087 Mkn_509 60 Yaqoob - Marshall 700278 2088 Fairall_9 80 Yaqoob - Marshall 700279 2089 NGC_4593 80 Yaqoob - Marshall 700280 2090 NGC_3783 170 George - Marshall 700281 2091 NGC_3783 170 George - Marshall 700282 2092 NGC_3783 170 George - Marshall 700283 2093 NGC_3783 170 George - Marshall 700284 2094 NGC_3783 170 George - Marshall 700311 2121 MCG-5-23-16 80 Weaver - Marshall 700340 2150 NGC_4507 140 Kahn Sako Marshall 700367 2177 IC_4329A 60 Madejski - Marshall 800119 1651 Zw3146 184 Canizares Wise Marshall 800147 2208 Hydra_A 60 Jernigan - Marshall 800161 2222 RXJ_1347.5-1145 100 Kahn Peterson Marshall
Last modified: 05/02/03
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