I'm in the process of reviewing RSpec to see if it will be the software of choice for the diffraction grating group. However, I thought I'd pass along a couple of preliminary projects for testing your grating.
Comet C/2014 Q2 Lovejoy. This is a naked eye comet in the south, and will be in the northern sky soon. Comets have lots of emission line outgassing, and it is variable. Monitoring the comet might yield some interesting results. Here are some other bright comets currentl visible:
http://aerith.net/comet/weekly/current.html
alf Com. While both components have similar spectral type, there could be some interesting effects during the January eclipse.
V838 Mon. Reports are that it is changing spectral type, from a very red star to more like a K giant. See if the molecular features are still there. Any emission at Halpha? This star has brightened by 2 magnitudes over the last couple of years.
V1369 Cen (nova Cen 2013) is still bright and starting to become visible in the morning sky for the southern observers. It should be in the nebular stage - what do the emission lines look like?
Other novae. What are other novae that have occurred over the last couple of years doing? A list and finding charts are available at
http://asd.gsfc.nasa.gov/Koji.Mukai/novae/novae.html
As W Vir becomes visible in the early morning hours, I'd like people to monitor this prototype pulsating variable. The Rc-band light curve has more scatter than BVIc, and my guess is that it has Halpha emission somewhere during its light cycle, most likely near maximum.
You might also generate a spectral atlas, choosing a few dozen stars from hot to cool and dwarf to giant. This will be a good reference for observers to see what each class looks like at this resolution. Jim Kaler has a nice list of the 170 brightest stars in the sky at
http://stars.astro.illinois.edu/sow/bright.html
which might be a good starting point to pick out examples.
Arne
How about V1357 Cyg? Over the past several months I have been noticing unusual variations between my Visual estimates and the CCD ones. Maybe there are some weird spectral lines coming into play that are causing these discrepancies?
This is a black-hole binary with relativistic jets, so all kinds of unusual things may be occuring here!
Mike LMK
I strongly recommend Richard Walker's Spectral Atlas. A wealth of knowledge.
http://www.ursusmajor.ch/downloads/spectroscopic-atlas-5_0-english.pdf
Terry Bolsen has been monitoring Nova Cen:
http://www.astrosurf.com/aras/Aras_DataBase/Novae/Nova-Cen-2013.htm
I'd also suggest checking out Buil's ISIS and John's BASS freeware software for grating spectroscopy.
http://www.astrosurf.com/buil/isis/isis_en.htm
https://uk.groups.yahoo.com/neo/groups/astrobodger/info
These are Windows programs, I'm not familiar with Mac alternatives.
Here are some projects for low resolution spectroscopy of variable stars, most of which are potentially do-able using the Star Analyser
Low resolution spectroscopy - OHP 2013 - Observer’s guide
http://www.astronomie-amateur.fr/Documents%20Spectro/SpectroscopieBasseResolution_En.pdf
and for some current ARAS projects using low resolution check out the Eruptive Star Spectrosopy Newsletters
http://www.astrosurf.com/aras/novae/InformationLetter/InformationLetter.html
Cheers
Robin
Hi: I posted The Death of Stars on the forum posting but, didn't get any replies and wondered was there a name for this disipline or study name as with the spectroscopy. Best HNL
See
http://www.aavso.org/aavso-special-notice-392
A spectrum of this object taken by a new SA200 user can be seen here confirming with high confidence that it is a type 1a
https://groups.yahoo.com/neo/groups/staranalyser/conversations/messages…
Robin
I had a couple of clear nights and got a chance to use the SA200. It is mounted in the filter wheel of a STT-3200 on a 106mm refractor with 25 mm between the grating and the chip. The calculated dispersion is 13.6 A/pixel.
The best focus was achieved using RSpec focus tool measuring the depth of the H beta absorption band. At best focus the zero order image was starting to look like a donut.
Using Arne's suggestion I used Jim Kaler list and picked out 25 stars visible from the patio (northern sky obscured) and took images varying between 1 and 15 seconds. The images were dark subtracted and analyzed with RSpec. The maximum ADUs of the first order spectrum was between 45000 and 60000 ADU. (I've measured the linear range on this chip to extend to 62000 ADU). I got better results using a non-linear calibration ( 4 points) in RSpec.
Here are representitive samples from each major spectral type.
I'd like feedback on their quality and suggestions for improvement. I copied the format that Jeff Hopkins used in his Orion project for presentation. Only the first order spectrum is shown ( trimed from 3500 - 8000 A.). Would it be better to show the zero order specturm in the graph.
Richard Sabo
SRIC
Hello Richard
Very nice results. Surprising you mentioned using 4 point non-linear calibration. I have noticed that my 2 point using zero, and Hb, never seems to give the right answer for Ha. I am at 22 A/px which masks some, but its still off.
I am interested to hear how you did your 4 point. No need to reinvent the wheel.
BTW: I like that you trimmed below 3500 and above 8000, I want to do something similar.
WGR
Gary Walker
The process is explained well in the last instructional video : "non-linear calibration". T-lhere are two tabs on the calibration screen. the non-linear tab has a grid that allows multiple pixel locations to be paired with correspending wavelengths. A non-linear function can be calculated and graphed using various polynomials. The steps are intuitive and easy to follow.
Richard Sabo
Good Morning Richard
Thanks for the info on the Non Linear Calibration. I would expect that using the zero order and Hb would be 2 good choices, depending on the star. Have you found other good choices that work most of the time. How about Ha? How about the atmospheric water lines at 7600? What do you recommend?
BTW: if you scroll down on the menu of videos in RSpec, you will find that there are additional ones after the NL Calibration.
I have a suggestion for your format from the Orion Project. I like the idea of having the elemental lines there. If you click on the tab labeled "Details", it gives the wavelenths of these lines and their names. This is very hand information to have and probably more important that just having the "Balmer" or "Type of Star" that the "Elements" tab has. What do you think?
Do you have a spectra of Delta Cas? I wanted to compare to mine.
WGR
Gary Walker
Nice to see you guys sprinting up the learning curve!
I thought I'd mention that you can add additional items to the Elements window . The "?" help icon on that window opens a pdf that shows how to create the text file.
Tom
Hello Gary,
That's a good suggestion - to show the "Details" in the Element dialog box.
The four points that I used for calibration were Hydrogen alpha, beta, gamma and delta using a Type A star.
A screen shot of the calibration grid is attached.
Sorry that I can't compare Delta Cas with you - my little telescope only sees the southern sky.
Richard
Hello Richard
Since you are North Challenged and cannot reach Dec 60 degrees, I have attached a Delta Cas screen shot for you!
I always thought Montana was north of Massachusetts. Do you live in South Montana?
WGR
Gary
Nice screen shot.
What is at wavelength 7660?
Richard
Hello Richard
I think that was a typo. Its the air glow at 7600. We really need a long wavelength standard above Ha. Anyone know of a good one?
Gary
Hi Richard,
Good work!
I will pop in here with the rational for the Orion Project profiles.
RSpec has an auto-scaling feature (note, that can be turned off, but is normally very useful). When the zero order spectrum is displayed this causes the first order spectrum to be displayed much smaller in amplitude/intensity. In addition, the first order spectrum line profile is shown in only a small part of the profile window. By trimming the first order spectrum, the resolution does not change, but you get a much bigger picture of the first order spectrum profile and features stand out much better. That makes seeing any change in the morphology easier to see.
Jeff Hopkins (187283)
Hopkins Phoenix Observatory
Hello,
[quote=HQA]
You might also generate a spectral atlas, choosing a few dozen stars from hot to cool and dwarf to giant. This will be a good reference for observers to see what each class looks like at this resolution. Jim Kaler has a nice list of the 170 brightest stars in the sky at
http://stars.astro.illinois.edu/sow/bright.html
which might be a good starting point to pick out examples.
Arne
[/quote]
if they would be of interest for reference purpose, I have compiled a good sample of calibrated stellar spectra of bright stars. They would be available, as a data file *.fit or *.dat. They are obtained with an Alpy600.
As an example, an spectrum of an A2 type star, from one of my last observing sessions is attached. Available spectra is of better quality tan this sample.
Regards
Miguel
Thanks Miguel for the generous offer.
How could I obtain a copy of your atlas - in dat?
Richard