Feder Observatory

A Blog for Minnesota State University Moorhead's Paul P. Feder Observatory

Archive for September, 2013


Problems with times stamp on 9/11, 9/12, 9/13 0

Posted on September 16, 2013 by Matt

I realized tonight that there was a problem with the observatory computer; the program that keeps the computer’s internal clock synchronized with Internet time servers wasn’t working.

It turns out the problem had nothing to do with that program. The IP addresses of campus DNS servers had changed so DNS lookup was failing.

When DNS was reconfigured the synchronization program reset the computer’s internal clock, adjusting it by -46.089 seconds. In other words, 46.089 seconds was subtracted from the computer’s internal clock.

Prior to tonight (9/16/2013) the last synchronization with the time server was on 8/20/2013 at about 5:45AM.

The bottom line is that the timestamp on images taken on the dates below are likely all off by some amount between 0 and -46 sec, but there is no way to know (at least at the moment) how big that offset is. On any given night the time difference between images should be very accurate. It is only the “absolute” time that is incorrect.

Observing Log, 9/13/2013 0

Posted on September 14, 2013 by Matt

WARNING: Timestamps in the files from this night might be off by as much as 46 seconds (in the sense of being as much as 46 seconds *ahead* of the actual UTC time). Relative times should be fine, but you cannot trust the absolute timestamp to better than 46 seconds.

Conditions tonight were good, but not perfect. Based on satellite images of the area there was a bit of light cloud cover around midnight that then cleared and by 1:30 more substantial clouds were getting close to coming in.

The only target tonight was an exoplanet, Kelt-1 b, chosen for two reasons:

+ The time of the transit fit nicely between the end of the public astronomy night and when the clouds were forecast to arrive.

+ The magnitude of the transit is very small, about 6 mmag (that is, milli magnitudes).

We should be able to detect changes that small but it will be an interesting test of what we can do.

All observations were done in the R band. For exoplanet observations you want as much light as you can get, and the R band is wide and its peak corresponds with the peak sensitivity of our camera.

Observing Log, 9/12/2013 0

Posted on September 13, 2013 by Matt

WARNING: Timestamps in the files from this night might be off by as much as 46 seconds (in the sense of being as much as 46 seconds *ahead* of the actual UTC time). Relative times should be fine, but you cannot trust the absolute timestamp to better than 46 seconds.

Conditions tonight were similar to conditions the previous night–excellent! I was outside several time and saw no clouds.

The observing plan was largely the same as 9/11/2013: MY Aql, then SA113 when it was at about the same airmass as MY Aql, then back to MY Aql. Tonight I took multi-color shots when MY Aql was around the same airmass as SA113.

Then switched to V0440 Lac for several hours, followed by EY UMa and, when it was at the same airmass as EY UMa, the standard field SA92. As with MY Aql/SA113 the shots at about the same airmass were taken in BVRI.

Observing Log, 9/11/2013 0

Posted on September 12, 2013 by Matt

WARNING: Timestamps in the files from this night might be off by as much as 46 seconds (in the sense of being as much as 46 seconds *ahead* of the actual UTC time). Relative times should be fine, but you cannot trust the absolute timestamp to better than 46 seconds.

Conditions were great tonight–good seeing (5-6 pixels FWHM) and not much temperature change so focus didn’t change much.

Air temperature at the start of the night was 62F and focus set to 2850.

Only one problem: MaxImDL had been set to do a “Simple AUtodark” which means, I think, the first several images of MY Aql and the standard field SA113 are unusable. All of the autodarked ones are in a clearly named subfolder of the data folder for this night.

Other than that things went fine.

All observations were in the R filter.

The targets for the night were:

+ MY Aql and the standard field SA113 observed at about the same airmass.
+ V0440 Lac
+ EY UMa and the standard field SA92 observed at about the same airmass.



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