| | 202 | |
| | 203 | === 3b If you are Observing in the 2017B semester: === |
| | 204 | The json files that are generated by the strategy code (mstrategy) will require a very large slew near the end of the night (~09:40ut = 02:40am) which will take you from the west end of the DESI North Galactic Cap footprint to its eastern end. The problem with this is that the system times out during the long slew, and this causes it to crash. |
| | 205 | |
| | 206 | The procedure until further notice is to break each new json file that is created in the ~mzls/obsbot/ directory into two parts at the point of this large slew. (This will not be necessary tonight, since you will be stopping observing at 00:27am, but it will be an issue for all your full nights.) This means that the observing script with which you start the night will terminate at around 2:40am. At this point, ask the telescope operator to slew to the first position on the eastern side of the NGC. Once the telescope has reached there, then restart mosbot by executing |
| | 207 | python mosbot.py pass1b.json pass2b.json pass3b.json —adjust —pass=3 —exptime=100 |
| | 208 | (where all the — are really two dashes). This will allow this system to continue without timing out during the slew. |
| | 209 | |
| | 210 | |
| 319 | | 1. At start of night, check telescope pointing (see item 8.4 above; you should already be there!) and zero the telescope coordinates using a bright star placed on the telescope boresight (defined as the center of the mosaic3 focal plane; ''i.e.'' in the chip gaps).[[BR]][[BR]] |
| 320 | | When taking the image of the bright star, make sure to create an OBJECT script with NGUI (not a TEST, because MOSSTAT will ignore it), zd filter, 1 - 5 sec exposure. Watch for MOSSTAT to process the image and report the RA, Dec offsets. If mosstat fails, it could be because (a) the telescope is mis-pointed, (b) the telescope is out of focus (set the focus approx using the formula above and try again). Once you are able to determine offsets, give these offsets to the OA with '''opposite''' sign. That is, if mosstat reads "RA,Dec offsets = -15.34, 18.32", then you need to provide the OA with the offsets of +15,-18 to zero the telescope coordinates.[[BR]][[BR]] |
| 321 | | You can take another OBJECT frame if you want to check to make sure the offset went in the right direction. |
| | 329 | 1. At start of night, check telescope pointing (see item 8.4 above; you should already be there! For B-semester observing, use the pointing coordinate 270.0, +60.0) by doing the following: |
| | 330 | (a) create an OBJECT script with NGUI for 5 sec with the zd filter (do not create a TEST script, because MOSSTAT will ignore it) |
| | 331 | |
| | 332 | (b) Execute it, wait for it to readout completely, and make sure that it appears in your data directory; if it does not, use the "Update Status" button on the DHS GUI |
| | 333 | |
| | 334 | (c) Once the image is processed by copilot, the bottom panel on the copilot plot will print the pointing offsets. Give these offsets to the OA with '''opposite''' sign. That is, if copilot shows numbers (-15.3,+18.3), or if mosstat reads "RA,Dec offsets = -15.34, 18.32", then you need to provide the OA with the pointing offsets of +15,-18 to zero the telescope coordinates.[[BR]][[BR]] |
| | 335 | |
| | 336 | If this process does not work for some reason, then you can also zero the telescope coordinates by using a bright star placed on the telescope boresight (defined as the center of the mosaic3 focal plane; ''i.e.'' in the chip gaps). As before, when taking the image of the bright star, make sure to create an OBJECT script with NGUI (not a TEST, because MOSSTAT will ignore it), zd filter, 1 - 5 sec exposure. After centering the bright star, return to the first target field and use the above procedure to determine the pointing offsets - do not use the copilot or mosstat results based on the bright star image! [[BR]][[BR]] |
| | 337 | |
| | 338 | If mosstat or copilot fails, it could be because (a) the telescope is mis-pointed, (b) the telescope is out of focus (set the focus approx using the formula above and try again). [[BR]][[BR]] |
| | 339 | You can take another OBJECT frame if you want to check to make sure the offset went in the right direction. |
| | 340 | |
