This day, 1 year ago…
… Amar and I were at the gate of the observatory, seeing off the group of M.Phil students working under Dr. Shylaja after a rather unproductive night. I can’t recall whether we had slept at all in the past 24 hours. Anyway, such are the times when sleep didn’t matter. I would’ve probably spent the day at the computer room in the mezzanine floor, telling people back at Bangalore my experiences, posting on one of those mailing lists, playing around with my newly acquired acquaintance – IRAF, or checking the SB What’s Observable site on JPL and noting down RAs and Decs of Vesta or some other asteroid.
That night was a very eventful night indeed. Amar and I probably became two of the few fortunate amateur astronomers in India who would’ve gotten to use a 40″ telescope, and even look through it.
The night of 12th June 2007 was pretty eventful for us. We had Mr. K. Kuppuswamy on duty, to operate the Zeiss 1m telescope and the PixCellent 1K CCD camera attached to it. The skies were clearing, but there was lightning at a distance in the north. We were walking on the corridor along with Mr. Kuppuswamy, learning about the joint discovery of Uranus’ rings, about how it was an observation of Uranus’ occultation of a star from 4 observatories (including the Kuiper Airborne Observatory, which is credited for this discovery) and how Dr. J C Bhattacharya was looking through the eyepiece and Mr. Kuppuswamy at the photomultiplier’s graph-sheet recorder noticed a sudden drop of the number of counts, waiting for the lightning to subside.
Finally, we went in and switched on the console, after the lightning became less. But the humidity was rising. We quickly took spectra of each of Jupiter’s moons, 6 spectra of Jupiter (in different slit positions) and the spectrum of Vesta. In between somewhere, Mr. Kuppuswamy was taking the comparison spectrum and we noticed dew formation on the CCD. He pumped in nitrogen. The dew went away. We had continued our photography. Soon, the Nitrogen would no longer help, not even a continuous supply. We shut down the CCD and did some visual observing at the eyepiece of the spectrograph, just for fun!
It was a nice experience for all three of us. We requested Mr. Kuppuswamy to slew to M22. I went to the UAGS’ eyepiece and saw an “Open cluster”!!! Such was the resolving power of the 40″! We slewed to M27 sometime, but it required extreme averted vision – the night wasn’t very clear, and the f/13 scope’s magnification was such that M27 filled the whole eyepiece field of view!! We also slewed to “Blinking Planetary” in Cygnus. We could see the blue colour easily and I don’t remember whether or not we saw the central star. It was a good sight, though.
Jupiter through the 8″ f/15 finder scope was probably the best view of Jupiter I’ve had till date. The amazing refractor from Zeiss is only a finder scope for the 40″!! To center an object, you first take note of its RA/Dec, slew the telescope till IIA’s Dome Control program reads the same, then center it in the 8″ (I don’t remember if the 4″ was functional. If it was, we’d have had to center it there first), then in the eyepiece of the UAGS of the mighty 40″!
I still appreciate the beautiful complexity of IRAF. I managed to install it finally and it now works. I processed today, 1 year later, the images taken about 364.8 days ago! (Please bow down to my postponing skills). And seeing the results today bring to me almost the same joy that the experience of taking them did.
IMPORTANT NOTE: I have not confirmed whether I have copyrights for these images. Although these images have been uploaded, they belong to Dr. B S Shylaja of the JNP. I will be verifying with her the copyrights of these images shortly.
These spectra were taken with the Universal Astronomical Grating Spectrograph (UAGS) and PixCellent 1K CCD camera with 2×2 binning at the Zeiss 1m telescope at the Vainu Bappu Observatory, Kavalur. Thanks to Dr. Sunetra Giridhar, Dr. B S Shylaja and the Director, IIA for giving me an opportunity to avail these spectra.
I didn’t have the Fe-Ne comparison chart, so I had to virtually cook-up values for spectral lines looking at this, and comparing the spectrum of Vega that we took on 9th June 2007 with this. Interestingly, the spectrum of Vega matches pretty well and it puts what I think is the H-Beta line at 4879 angstrom instead of 4861 angstrom, which is an error of 0.4%!
This is after removing a vague continuum spectrum from Jupiter’s spectrum above. We can again see the H-Beta line @ ~486nm and the feature at the Sodium and Helium D lines. This doesn’t mean the Jupiter is full of Hydrogen, but is because the light from Jupiter is reflected sunlight! I need to learn and subtract the Solar Spectrum from this to get a pure Jupiter’s reflectance spectrum.
This is the spectrum of Vega, after removing the continuum. The continuum matched very well in this case (pure blackbody!) and once that was removed, the features became more clear. Once can see the same features of Hydrogen and Helium (?) at 486 nm and 587 nm. Wikipedia lists a diatomic oxygen Fraunhofer line at 628nm, and I was wondering if the small peak at a similar location could be that. I have not subtracted the sky spectrum. I’m yet to check out the possibility of doing this.
I really enjoyed the processing. It took me all night. I didn’t have my notes on IRAF commands, so it was partly from memory that you had to do something called ‘epar apall’ and from Google. These documents helped me:
1. The Zen of IRAF for the CCD Processing part
2. The IRAF FAQ on exporting for the final image export
3. User’s Guide to reducing Slit Spectra with IRAF for teaching me how to set reference spectra the hard way (for some reason, epar refspec wouldn’t work and would trim out the imh from the reference spectrum image name. I don’t know, it didn’t seem to work for me.)
There were a lot more that I can’t remember / didn’t bother to copy URLs of / that were random “Googlings”.
It was fun reviving something that I learnt an year ago and finally getting satisfactory results!