Glad to hear you have a slit spectrometer (L200) on order. I hope you also ordered the 1800 grating as you will need that to reach the required eta Car campaign resolution of R~5,000.
One thing delaying the new shipments is that Ken needs to fully check out the final JTW production product and that is not made easy by the recent very cloudy nights we have been having in Melbourne.
Good ... about the 1800 grid.
Good question ... about Ken having the JTW L200. The last time I asked him, at least 2-3 weeks ago, he said it was in transit so I would be surprised if he doesn't have it by now.
I see that Ken has just posted (on Aatronomical_spectroscopy group) that
"All the initial testing of the latest JTW build of the Spectra-L200 has been successfully completed. Mark will be confirming shipping dates....."
I hope you both get your relevant L200 orders soon, as eta Car is fast approaching periastron and the spectra is evolving nicely. I'm in virtually daily email contact with the various pros involved with ground and satellite data (mainly X-ray) and am happy to pass on the interesting stuff. As this data is not for general publication at this stage I will need Jon's email (I have Terry's), so please contact me at: spectrasouth at bigpond dot com.
As my contributions to this campaign have recently dropped off, due to lousy weather followed by my visibility of eta Car being increasingly restricted by trees, your contributions will be greatly appreciated.
Finally getting some clear sky and I obtained another low-res spectrum of Eta Carinae tonight. I haven't done anything other than create the bar yet but I thought I'd post this image which has the spectrum of 27 June 2014 at top and 22 July 2014 at bottom.
These are at full camera resolution, from L image size (5184 x 3456 px), stacks of 15 & 13 subs resp and all 9-sec exposures using SA100 grating & Canon 650D camera with 200mm lens. You may need to expand to full size when the image opens.
The problems in accurate calibration & getting other quantitative data of course include lens aberrations, no flats, etc etc etc.
Thanks Rob, would you mind add some comments or pointers to the image to help me interpret the lines?
Bo
Hi Bo - I've done the full graphic, attached. It has the visible hydrogen emission lines marked, hope that helps.
The other ones were posted just to give an idea of the detail (real & otherwise!) at full camera resolution. A lot of fine detail is lost in creating the 'pretty' graphic attached.
Here's the full-resolution with three Eta Car spectra and some stronger emission lines marked. Not sure if identification is 100% correct (should HeI be HeII?). I used a pretty old paper, Identifications in the Spectra of Eta Carinae and RR Telescopii, here: http://mnras.oxfordjournals.org/cont....full.pdf+html
The calibration is probably OK to about +/- 0.5nm (+/- 5Å).
Rainy/cloudy here again after a very welcome short break. Hoping to follow Eta Car closely through periastron passage if the weather allows - trust things will work out well for those undertaking the valuable hi-res spectroscopy!
Cheers -
Last edited by Rob_K; 26-07-2014 at 12:18 PM.
Reason: changed link
Got another low-res spectrum of Eta Carinae tonight, a real battle against cloud banks both drifting through and making-&-breaking. Spectrum from 22 July (top) included, both presented as bars at full camera resolution. 'Spears' included at bottom. Canon 650D & 200mm lens, SA100 grating, 20 x 9 sec (28th), 13 x 9 sec (22nd), ISO 6400, F/5.6, L image size. Scale is 0.22nm/pixel, or 2.2Å/pixel.
Forecast for the next week doesn't look very promising...
I've also been taking spectra of eta car with my newly recommissioned L200 spectrograph.
An interesting star.
Terry
Good stuff Terry, hope you keep posting them! Rain's continuing here but might be a break over the next few days.
As a matter of interest I prepared a comparison graphic between your spectrum and mine of a few days before, hope you don't mind. Pleased to see that the SA100 is picking up all the major features of the high-res spectrum. What mine lacks of course is accurate calibration due to lens aberrations, the dispersion of yours (yours had to be severely 'concertinaed' to fit mine) and precise information on relative intensity due to vignetting (no flats!) & probably a non-linear camera response (??). But that's the difference between hi & low-res spectroscopy!
Rain? Bloody well snowing here. Plus I have no spectroscope. I guess I'll have to wait another 5.5 years ...
Eek! The hills all around the town I live in are dusted with snow, hope that's as close as it gets!
About the 5.5 years, it's not guaranteed Jon. It would be dreadful if you missed out on periastron altogether because EC went supernova. That would be damned inconvenient...
My low-res spectrum of Eta Car from tonight, following a couple of unusable spectra from previous two nights. Bar at original size is here (click to enlarge if necessary, 3193 px wide): http://i727.photobucket.com/albums/w...t.jpg~original
