Summary: Some clouds at the beginning but cleared up later. Seeing was mediocre initially (~1") but improved to ~0.8". We have executed 2 OBs for E. Olszewski's program and 8 OBs for L. Jiang's program. Although the overall operation was fairly smooth, we note the following problems we encountered:
  • Problem 1 - Blue Channel focus was persistently bad. Images were elongated even after focusing/collimating with dofpia. Focus improved after Olga adjusted slightly the focus offsets for the g and r filters, but we're not sure if this was the cause.
  • Problem 2 - Sky background with the F970N20 narrow-band filter was x4 larger than the ETC prediction.
  • Problem 3 - Connection to the wiki page was often extremely slow, making it difficult to update the log.


1:50
  • Opening the dome. Clouds in the west. Expected to move in gradually.
2:00
  • Taking twilight flats: blue-g,r; red-r, F970N20
2:30
  • Pointing check.
2:50
  • Focusing/collimating at the position of UMaIgr_pos0. Seeing ~1".
3:20
  • UMaIgr_pos0 (E. Olszewski) started; Still clear overhead.
    Focus not good with the first two g-band frames. Images look elongated.
    Focus good with r-band frames.
3:35
  • OB interrupted after two images.
    Running dofpia again.
3:40
  • Restarting UMaIgr_pos0.
3:55
  • OB interrupted again due to bad focus in the g band.
    Focusing/collimating.
4:10
  • Restarting UMaIgr_pos0 (E. Olszewski).
4:25
  • Patchy clouds moved in. Kept running the OB.
4:40
  • UMaIgr_pos0 completed.
    Waiting for clouds to clear up.
5:15
  • Taking test images to check the cloud condition.
5:30
  • UMaIgr_pos1 (E. Olszewski) started.
    Bad focus in the g-band images. Images elongated.
    Focus with the r-band images looks OK.
    Not clear why the blue channel focus is so persistently bad.
6:00
  • Taking test images by setting the blue channel as the master for guiding.
    No improvement with the blue-channel focus...
6:10
  • Moving to the next target, the IRAC dark field.
    Focusing, collimating & checking pointing with a nearby star.
    Slewing to the IRAC dark field and focusing/collimating again.
6:30
  • IRACdark_grN1 (L. Jiang) started. Red channel is the guiding master.
    Seeing ~ 1.4" @ airmass=1.6; Sky looks clear now.
    The sky background x4 larger (~13,000 DN) than what is predicted by the ETC (~3000 DN)!
7:10
  • IRACdark_grN1 (L.Jiang) started with a different starting position to avoid a nearby bright star.
    Guide star was not found in the red channel; OB aborted.
7:20
  • IRACdark_grN2 (L. Jiang) started. Focusing/collimating.
7:55
  • IRACdark_grN3 (L. Jiang) started. Good seeing in red: ~0.85"; ~1.2" in blue. Focusing/collimating.
8:35
  • IRACdark_grN4 (L. Jiang) started. Focusing/collimating.
9:20
  • IRACdark_grN5 (L. Jiang) started. Seeing ~0.8". Focusing/collimating.
10:00
  • IRACdark_grN6 started but immediately aborted. Wanted to update the focus offsets in the Blue Channel to improve focus.
10:15
  • IRACdark_grN6 (L. Jiang) started with new focus offsets to g and r in the Blue Channel. Focusing/collimating.
10:50
  • IRACdark_grN7 (L. Jiang) started. Blue Channel focus better now but not quite stable. Images still get elongated sometimes. Seeing ~0.8" in red, ~0.9" in blue. Focusing/collimating.
11:30
  • IRACdark_grN1 (L. Jiang) started. Returning to the first OB. Morning twilight starting.

-- EiichiEgami - 15 Apr 2010
Topic revision: r5 - 16 Apr 2010, XiaohuiFan
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