Dear all
A very bright nova has been discovered in Del. http://www.cbat.eps.harvard.edu/unco...3+2046041.html
It is very bright at around V mag 5. I took images and spectra of it tonight.
I was limited to 4 sec exposures with a V filter as it saturated with a longer exposure.
The spectra is taken with my LISA spectrograph. This satureated with exposures longer than 45 sec.
This is the brightest nova in quite a few years and will be interesting to follow as it changes.
I clearly picked a good week to start dabbling with spectra :-)
As a complete newbie I feel a bit embarrassed following on Terry's marvelous spectrum, but I also got something with my SA100 tonight.
Now, everyone seems to be saying that it is "clearly a Fe Nova". I'm about to embark on some self-education, but what is it about the spectrum that leads to this deduction? Forgive my ignorance, but I guess this is a good place to ask.
(I should point out that these are actually the first emission lines I have ever captured for myself. I'm quite excited)
[BTW, thanks for the tips from everyone and especially Ken in the other thread. I seem to have my head around focus, calibration and instrument correction now. At least, I'm getting results that look a bit meaningful]
In appendix (Table A1) of paper "Origin of the ‘He/N’ and ‘Fe II’ Spectral Classes of Novae" (R. Williams) there is a finding list for optical emission lines http://arxiv.org/pdf/1208.0380.pdf
I clearly picked a good week to start dabbling with spectra :-)
As a complete newbie I feel a bit embarrassed following on Terry's marvelous spectrum, but I also got something with my SA100 tonight.
Now, everyone seems to be saying that it is "clearly a Fe Nova". I'm about to embark on some self-education, but what is it about the spectrum that leads to this deduction? Forgive my ignorance, but I guess this is a good place to ask.
(I should point out that these are actually the first emission lines I have ever captured for myself. I'm quite excited)
[BTW, thanks for the tips from everyone and especially Ken in the other thread. I seem to have my head around focus, calibration and instrument correction now. At least, I'm getting results that look a bit meaningful]
I was going to concentrate on getting a spectrum with the Star Analyser last night but incoming weather meant I had to try too early and the area never fully cleared the trees at my place. I didn't have any charts and although I had a pretty good idea where the nova was I could never see enough sky in narrow gaps in the trees to pin it down!
In an attempt to get something (anything!) I resorted to shooting the gaps from various angles using a wide 55mm zoom and as luck would have it I did get the nova in a number of frames. Rough and poorly exposed though. I did a little stack of 6 barely-usable frames but it's got me a little confused. I would have expected to see at least a bright H-alpha line but the spectrum appears featureless (ignore the lines, just noise).
I've attached a composite image, top is a crop from a late frame showing the nova and its spectrum (as well as the spectra of the main Delphinus stars) and at the bottom bar spectra of the nova, and T Pyx for reference.
Any comments or advice as to why I mightn't have picked up the hydrogen emissions? Thanks.
Edit: the bar spectra aren't exactly the same scale - I just roughly matched the colours as they were shot at different scales. OK for the purposes of the exercise though...
Rob,
Good catch under the circumstances...
If you check out some of the other SA100 shots on the forum you'll see that when the resolution is low the Ha peak is not very evident....
If you can get around 8A/pix dispersion and a good exposure the emission lines should show....
(He says roping down the observatory roof from the hi-wind and rain coming...)
Rob,
Good catch under the circumstances...
If you check out some of the other SA100 shots on the forum you'll see that when the resolution is low the Ha peak is not very evident....
If you can get around 8A/pix dispersion and a good exposure the emission lines should show....
(He says roping down the observatory roof from the hi-wind and rain coming...)
Thanks Ken, that's pretty much what I suspected. Awful spell of weather isn't it?
The spectrum I posted above, straight after Terry's, was taken with the Star Analyser 100. 8.8A/pixel. Both the alpha and beta emission lines are pretty clear :-) It's a single 2-sec sub. I've now got a much less noisy one that is a stack of 6 subs with darks and bias.
For what it's worth, here are two spectra I got with the SA100 on 15 and 18 August (as it happens, the date on which the Balmer emission lines had dropped to their lowest levels before brightening again)
Well done Terry, I think you can expect to be seeing your name in a published paper from this one too.
In case anyone here isn't following it there is a thread at http://www.spectro-aras.com/forum/vi...2&p=2703#p2703 where Terry and others in Europe (why is spectroscopy so popular in France?) are posting their results. I've been having to enjoy the nova vicariously as I've been under almost continuous cloud since the outburst Hoping to get my SA100 on it before it fades out, fingers crossed.
This is definitely a good month to begin a journey into astronomical spectroscopy!
I used my new SA100 for the first time last night. The SA100 was screwed onto the 1.25" nosepiece of my QHY5 with spectra processing using a trial copy of RSpec. The scope used was a Long Perng 80mm f6 achromat.
After having taken a test image with my 400D to confirm the location of Nova Del 2013, I calibrated first on Fomulhaut, then centred on Nova Del 2013. I had to swap out the QHY5 between Fomulhaut and Nova Del so that I could centre the new target. I found Nova Del much harder to focus on than Fomulhaut, but hopefully I can finetune the workflow so that I dont need to change cameras and refocus everytime I change targets.
I too am getting acquainted with my new SA100, and finally managed to get a very dodgy spectra of the nova last night. Also using a QHY5 but with a 10" dob. I'm having to do 'drift' spectra, and the nova is pretty much at the lower limit of magnitude to do this with my setup I think. Almost no signal from the continuum, but the emission lines were easily visible, it was obvious I had the right target in the live view.
My efforts are attached and should provide a suitably low bar for everybody else to feel better about their results
Richard,
A couple of comments..
Can you add a flip mirror in front of the camera? Makes it much easier to aquire the target.
( I can use GOTO and CdC with the NEQ6pro to just "drop" the target onto the grating....)
It's standard to present the spectra with the zero order to the left - this gives a spetrum orientated with blue to the left and red to the right - usually needed when you start to do calibrations...
Good start.
Well done.
Richard,
A couple of comments..
Can you add a flip mirror in front of the camera? Makes it much easier to aquire the target.
( I can use GOTO and CdC with the NEQ6pro to just "drop" the target onto the grating....)
It's standard to present the spectra with the zero order to the left - this gives a spetrum orientated with blue to the left and red to the right - usually needed when you start to do calibrations...
Good start.
Well done.
Thanks Ken. Glad to hear I'm on the right track!
A flip-mirror is a great idea - I will need to add that to the shopping list. If I had used my normal setup procedure I would be able to "drop" targets onto the sensor as well (especially at only 480mm FL), however it was a last minute decision to set up the second mount for spectroscopy (I dont have a permanent setup) and so I didn't finesse the polar alignment / GOTO model.
Re the spectra I posted before, I had the zero order to the left and had calibrated on an A-type star. I had just cropped the curve. I have now gone back and selected frames with better FWHM for calibration and presentation. Hydrogen Balmer lines are also shown for reference.
btw I was wondering about attaching the 1.25" nosepiece with the SA100 to a T-ring with my full spectrum modded 400D (which has both UVIR and anti-alias filters removed) - I suspect that this camera has a wider spectral response than the QHY5, as well as having a wider FOV, less noise, 12 bit ADC, and the ability to capture longer exposures.
However using the RSpec calculator it tells me that my resolution will be 7A/pixel with this setup. Is this too small? The two scopes I would be using are a Vixen VC200L at f9, or a 80mm f6 refractor
With an f5 system, there seems to be a "sweet spot" around 8-10A/pixel.
Going <8 A/pixel is like "empty magnification" - makes the spectrum larger but with no improvement in resolution.
You should also aim to have the spectrum horizontal across the chip. This reduces the likelyhood of introducing artifacts during the processing.
Onwards and Upwards.
Hoping to get my SA100 on it before it fades out, fingers crossed.
