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I am no expert, but according to the Spectral Atlas for Amateur Astronomers (Walker), you see Fe I/II emission lines in Be stars of classifications e3, e3+ and e4 – maybe weak in e2 class (psi Persei).
Tony Rodda has posted his spec of the star. He sees the Fe emission too. Click spec database on the right, type psi per into the box and click fetch spectra. David
So the weather there is no different to here then! I have my fingers crossed for a bright supernova (mag 11-13), well separated from the host galaxy nucleus, and present in a relatively sparse star field. I would like to try to get a spectrum using my slitless StarAnalyser. Is this too much to ask? 🙂
I managed to stack 20 x 10s frames. Midpoint of capture 21:09:25 UT. It’s bright! See also the attached png.
He was clearly a talented and well-liked man. I have just read his obit in the Times – Nick is quoted directly from his forum post.
Yes, I think Hugh ‘saves’ the Bahtinov mask diffraction pattern after achieving a sharp spectrum on an A type star, and then targets that pattern on the next target star. Sorry, because I am new to it I am not including the pertinent info! David
Thanks Robin. I think next on the shopping list is one of these Bahtinov masks – focusing is clearly one of the most tricky parts for a novice like me.
Yes, with the frames I look last night: for some, a two point calibration with zero and hydrogen beta seemed to work very nicely, with the alpha, beta, gamma and delta Balmer lines superimposing precisely on target in RSpec. In other frames this wasn’t the case. I guess it is just an effect of seeing? I am looking forward to seeing the spectra of SN2018gj that will appear over the next few days. I note you are discussing the uncertainty around the SNII subtype on the ARAS forum. David
I’ll not do any sharpening. It was easy enough anyway to scan through the frames by eye and then select the best; no computer programme is required for that. The seeing yesterday was extremely bad – as unstable as I’ve ever seen it would not be an exaggeration.
I’ve posted a much better effort on my member’s page. With my first go, I thought stacking and sharpening a load of images (a la planetary imaging) would help things, but I think it actually blurred the spectrum – and the bit depth was 8 bit anyhow. This time I was careful with focusing and made sure the exposure wasn’t too high. I think the result is much better. Unfortunately the ADU of my camera is 14 rather than 16 bit, so there’s not quite as much data as there could be.
Yes, I think overexposure is likely. I’ll look into the brightness values. Vega of course is low in the evening, and with this being early days (in spec) for me, I thought I’d go for a convenient target from my backyard. Thanks Hugh – David
I’ve carried out my first capture. Not an ideal target I gather, but the weather isn’t cooperating! I’ve done the wavelength calibration – with the star image and hydrogen alpha line. Focus is definitely something I’ll work on; and exposure time too. David
In-line image cropped