My 1st spectrum and hope for your comment

[Firefly]

PARAMETERS for Aquisition of Altair:

Time: 2012-08-15
Observatory: Tianjin, CHINA E117-15-10; N39-09-35
Instruments: C11 Lhires3-2400 QHYIMG2Pro [SONY 285AL CCD] , Watec120N+ for guiding [manual guide]
Seeing & Transparence: not very good, thin fog, LM for naked eyes is 2~3
Temperature: 25℃ Barometer: 1010 Humidity: 100%
Slit: 23μm CCD temperature: -10℃
Aquisition time: 3 x 300s
Lamp for flat: National Video lamp 300W, distance to telescope is about 1m, without any piece of paper to cover the aperture, exposure 12 x 2s

spectrum is only treated to 1c level


ADDITIONALLY: have a look at picture "confusion". How to use correctly 1,2,3?? Especially 3, saling spectral region, is the value correct for my situation? If I use 1200l, or 600l, what shall be the region? Can you explain deeply & clearly about these three parameters respectively? I can never find the explanation in Mr. Buil's tutorial.

Regards,

Dong . Li (李冬)

[Thierry Lemoult]

Hello 李冬)

Nice altair spectrum spectrum.

For flat acqusition. It's preferable to use a diffuser at the entry of the scope.

Your neon acquisition is a little strange. I do not understand what append in the top of the picture.
Here my typical neon picture. Perhaps, you need to adjust the focus.

I use a similar configuration: LHIRESIII, ATIK314L+ (ICX285AL) , grating 2400 grove/mm. You do not need to touch the setting 1 and 2 at the begin. So let it's like that.
The third setting define the region of the spectra that ISIS will use to calculate a global factor to normalize the spectrum. This region should not contains too many absortion line. The goal is to applied a factor is to obtain a value close to 1 in the region you defined. That's a usual to try to obtain the value 1 on the continum region of the spectrum. I look on my setting, i use: [6630A, 6645A].

Regards

Thierry

[Firefly]

Hello, Thierry:

These days, at the time of famous OHP, I at home arranged a little OHP I mean that I have read and learned carefully and hardly through the tutorial, including the advanced version [so far to part 3 of it], so hard it is for me, maybe as I am a new one in the wonderful spectral world. I feel that I have gotten many great hints & help.

1. About the neon. Because I made out my own LHIRES3 from blueprints to the final real product step by step, and especially at that period of time, I HAD GOTTEN MANY WARM HELP from Mr.Thizy, he's so kind~~ it was such a hard work for me to make it out. There must be some diveations in the making of components, i.e., the positions of rivet nuts perhaps move up/down or left/right to the standard one, then slit does not sit at the accurate location. But I do not feel that this affects the result, do I?

2. In my "Profile Display" window, I put the cursor to the left and the right, it is 6500 and 6620,respectively. "I look on my setting, i use: [6630A, 6645A]. " I can not get 6630 and longer more. Both of us use 285AL CCD, why can you get that? Can I use a region between 6500~6620 where there is few absorption lines

3. In the "Settting Tab", ISIS defaults "Spline" as the interpolator type. But in most situations by reading through tutorial, I find it is "Bilinear". Can you give me some explanation about how to select correctly between them at different treatment?

All my best,
Dong .Li (李冬)

[Thierry Lemoult]

1. Congratulation for your LHIRESIII construction. Your result look good. For neon, i suspect ISIS will use only the part of neon close to the spectrum position. So the little difference un the top of your image should not affect the result.

2. Sorry, i give you the range i use with my LISA spectrograph. I reload a spectrum of altair. I have have approximatly the same range than your spectrograph. Se my result here. This result it's my first spectrum acquire at OHP2011. So do not look to deep, it's not perfect. The spectrum start at 6500A and stop a 6612A. It's verry close to your spectrum.
In the range 6590 to 6605 the spectrum is approximatly flat. So you can use such a range. And remember that this is only a display factor. This factor have no real meaning. We do not do a absolute flux measurement.

_altair_20110805_019.png (5.7 KiB) Viewed 5224 times

3. I don't know what is the best choice. i suppose that depend of your spectra.

Regards

[Firefly]

Hi, Thierry:

Many thanks~~ Yes, I agree with you, about neon line, I feel that is the reason why Y position is so important.