Adam Ginsburg's blog

Articles by Adam (keflavich@gmail.com)

• Observing 10/20

  I don't have a better place to post this one, so here it is:

  

  My automated fitter (Gaussfitting Cube Collapser) has come a long way. I now adaptively choose to fit 1, 2, or 3 Gaussian components to output to a data cube. The purpose of that code is primarily to find a two-dimensional way to display information about the 3D structure, specifically about the presence/absence of outflows. Outflows will inevitably be confused with multiple velocity components, but they are also likely to be convolved with them.

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• Observing @ GBT: Signs of good & bad data

  So far, all of the observations for the H₂CO densitometry project have been performed at the Green Bank Telescope. During a 10-day long observing trip here, I've learned a lot about diagnosing bad data.

  

  This first image shows TSYS vs Airmass for good data. The high outliers are just sources with continuum in them - the continuum is the source of the extra signal, not atmosphere.  The receiver temperature is a nice 20.6 K, and you get about 5 K extra per airmass, suggesting a zenith optical depth of 0.018 assuming a round atmospheric temperature of 300K.

  

  In the same style plot, there is a set of observations with low system temperatures: that stuff is good. There is also a set with clearly rising system temperatures, even at constant elevation. These data are bad. During this observation, the "blowers" that are meant to keep dew off of the receivers failed. Dew buildup on the receiver covers lead to higher optical depths and therefore system temperatures.

  

  Finally, this data set was totally useless. Ku-band is not particularly sensitive to water in the atmosphere... but it's still not a good idea to observe during a rain storm.  Note that the fitted receiver temperature TREC is nonsensical.

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• Observing run summary

  3 nights of worse than grade 4 weather (tau ~.4, i.e. the atmosphere is nearly opaque) have given me a few interesting results. 1. Non-detections of CS 5-4 in a few bright BGPS cores. My best guess is that the pointing was off, though, because I definitely got down to a noise level around 50mK. 2. Lots of CO 2-1 mapping, 13CO/C18O too. That means I can now use this plot: http://dustem.astro.umd.edu/pdrt/co3221web.html to try to measure the incident flux. 3. I can't do homework at the summit. Maybe it's just that I can't do stellar structures homework, but I really am not processing this stuff well. Damn. 4. Running at altitude uphill is really, really hard. All the running I've been doing the past N months has not even come close to preparing me. Need to correct that... 5. "I am inappropriate." I probably violate a bunch of those rules... the important ones... 6. gotta get back to the mountains. Really. Seriously. OMFG. 7. ARGH those papers need writing! Lots of it! For the next observing run, need the following: 1. Pre-prepared A3 rasters 2. Larger selection of summit music 3. Better sleep schedule preparation 4. More caffeinated drinks per night 5. Cloud cannons.

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• Observing this weekend

  whoops, never made this post. Turns out I got rained out - 3 inches of rain on my night. Sad, no DIS time for P Cyg.

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• Offset symbols?

  AG

  

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• Orion in the Infrared and Millimeter

  

  This composite image of the Orion A Giant Molecular Cloud star-forming complex shows infrared emission from the WISE and MSX missions in 4 micron (red), 12 micron (blue), and 22 micron (green) emission with Bolocam Galactic Plane Survey 1.1mm emission overlaid in yellow/orange. The Orion A region is frequently featured in astronomical images:

  • http://apod.nasa.gov/apod/ap110917.html
  • http://apod.nasa.gov/apod/ap120212.html
  • http://apod.nasa.gov/apod/ap120206.html
  • http://www.eso.org/public/images/eso1219c/
  • http://www.eso.org/public/news/eso1209/

  but its tail tends to be ignored. This quiescent region is the source of the next generation of stars, although the relatively small mass concentrations imply that no massive stars like the bright Theta 1C that powers the Orion Nebula will form. The infrared colors show all sorts of stars including protostars. The infrared can pierce through the dust and find young stars still forming. The green and blue bands also see diffuse clouds of dust being illuminated by the central stars of the Orion nebula. The yellow 1.1 mm dust emission shows the coldest dust that is shielded from external radiation. These cold clumps contain enough mass to form new stars...

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• Outreach Observing

  Some notes for this Friday... the ISS will rise at about 10:55 on Friday, July 18th, and 9:43 on Saturday, July 19th. Jupiter will be in the sky, but Venus and Mercury will not. Jupiter will rise in the Southeast

  Denver, CO   2008/07/16  10:15 pm   Sunrise/set: 05:46 am / 08:26 pmPredicted passes for: ISS         daylight-saving time enabled             Local   Duration   Date       Time    (min)   Approach     Max. elevation    Departure------------------------------------------------------------------------2008/07/17   02:57 am   <1  10° above N     10° above N     10° above NNE2008/07/17   04:30 am   5   12° above NNW   31° above NE    10° above E  2008/07/17   10:30 pm   <1  13° above WSW   15° above WSW   15° above WSW2008/07/18   03:19 am   4   10° above NNW   16° above NNE   10° above ENE2008/07/18   04:54 am   5   15° above NW    78° above W     10° above SE 2008/07/18   09:19 pm   5   13° above SSW   29° above SE    11° above ENE2008/07/18   10:55 pm   4   17° above WNW   25° above NNW   10° above NNE2008/07/19   03:42 am   5   13° above NNW   32° above NNE   12° above E  2008/07/19   05:18 am   4   16° above W     22° above SW    11° above S  2008/07/19   09:43 pm   5   19° above WSW   71° above N     10° above NE
  

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• Outreach this past weekend

  I did the thing at Vail, Starry Nights, and it went well.

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• P Cygni

  P Cygni is a neglected LBV. You search for Eta Carinae on google and get hundreds of epic images of the fella, but nothing of P Cyg! Not even my Fe II image, which is now reproduced here:

  

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• Parallactic Angle

  So it turns out parallactic angle and field rotation are essentially the same thing. While working on the data pipeline for the Bolocam Galactic Plane Survey, I've needed to deal with this. The parallactic angle is dependent on the alt/az, and therefore the time, of the observation. So using an RA/Dec in J2000 coordinates to get alt/az isn't going to work, because my observations weren't in 2000.0.... my best hope is that the PA in the NCDF files is actually the correct parallactic angle. YARGH!

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