ENR CTIO Blanco 4-m 2013-01-21

Monday, January 21, 2013 Telescope: CTIO Blanco 4-m Submitter: Bob Nichol Submitter Email: bob.nichol@port.ac.uk Observer Support: None Night Assistant: Alberto Alvarez Also Present: Hernan Tirado Gerdes, Old, Hoffmann Problems: In afternoon, exposure queue hung with flats with DECam interface saying TCS was unresponsive. Restarting the TCS solved the problem Comments: Bad seeing and thick cloud came in from roughly 00:15 local time. Much of the data was with seeing > 1.5 and had trouble guiding. Monday, January 21, 2013 (second half of night) Telescope: CTIO Blanco 4-m Submitter: Adam Miller Submitter Email: amiller@astro.berkeley.edu Observer Support: None Night Assistant: Alberto Alvarez Also Present: Chris Klein Problems: The beginning of our observations featured thick clouds and poor seeing, however, the tracking issues that affected our images from two nights ago were gone during an initial sequence of images that were 40 s exposures followed by slewing to another field. However, after ~30 images were taken the tracking issues returned (during a sequence of 20 s exposures followed by slewing). After the tracking issues, namely elongation in the images in the RA direction, persisted for ~1 hour, we paused observations and sent the telescope to zenith. We obtained a sequence of test images at zenith which showed no tracking issues. We returned to our field and continued observations - the elongation issues persisted at this point but the amplitude of elongation was significantly improved relative to the previous sequence. It appears that after a moderate slew (anything between 60 and 5 deg) the image quality is significantly better if several images are taken in a single location prior to initializing the observing sequence. This theory should be tested in greater detail. We would also not recommend exposures shorter than 20 s if they are to be immediately followed by slews. Also, the guider GUI was not updating with guiding information (though the guider did appear to be working throughout the night). Somewhat inexplicably at the very end of the night (after twilight started) the guiding GUI started working again. We performed a configure command with the observer console which may have led to this difference.