I have recently obtained this calibration lamps from Peak2Valley. I believe it was one of Ken Elliott’s original lamps! Neon-Mercury. Runs off 12V power supply do convenient to use outside.
The following explains why the light kept switching on and off when Lee and I changed the plug at RAG mid-monthly meeting last Friday!
It also explains the black ring under the lamp – this appears to be so that it can fit over 2 inch end of a spectrograph – will it do same on my CCDSPEC?
Notes on DADOS Calibration lamp
The Neon calibration lamp only shines in the dark due to a twilight switch. So incidence of extraneous light while taking spectra of this Neon lamp is avoided. Please fix the Neon lamp with its adapter directly at the 2 inch entrance of the DADOS spectrograph to focus DADOS and to take reference spectra. The brightness of this Neon lamp is adequate in this configuration.
However, the lamp is too faint to be used in front of a telescope. The visually perceived color “Neon red” is a quite unique color between dark-orange and light-red due to the spectral distribution of the emission lines.
Following my recent post:
Peter Hill asked me whether I had used the “subtract background” option in RSPEC to bring the baseline down towards zero on the spectrum – I had not done it and did not know what to do so I looked it up and here is the difference it makes……(below)
A dramatic improvement! Thanks Pete for the advice!
WITHOUT the “subtract background” feature being used (below):
WITH the “subtract background” feature being used (below):
This post follows on from this previous one:
Today (11/10/2018), I had a go at generating an instrument response curve in RSPEC software for CCDSPEC using Altair spectrum from 10/10/2018.
My Altair Spectrum from 10/10/2018 (LRO, CCDSPEC, Sky Watcher Equinox Pro 80mm):
Dividing Altair spectrum by smoothed A7V reference spectrum leads to instrument response curve below:
Applying instrument response curve above to Vega spectrum in RSPEC:
See following post for a follow up to this post 11/10/2018:
A new star tonight for me – Altair! I have not taken a spectrum of this star before. Being also an A type star (A7V), it was going to be similar to Vega (A0V). Therefore, I took a spectrum of Vega for comparison too..
Taken using CCDSPEC spectrometer with Sky Watcher Equinox Pro 800mm Telescope on alt-az undriven Manfrotto mount – hand-guided for 50 second exposures.
RSPEC software has some great reference spectra which I was able to use to calibrate these images this evening. Cross checked using my own image of Vega as reference spectrum.
Note Vega = A0V spectral type
Altair = A7V spectral type
The post below follows on from the above post:
On the RELCO starter spectrum below, my CCDSPEC spectrum is graphed against the ALPY spectrum from Three HIlls Observatory from Robin above, and I have marked the lines I identified together with those lines that ISIS use for calibration – this gives some more lines for me to use at LRO.
Comment from Robin at Three Hills Observatory (https://stargazerslounge.com/topic/226911-neon-lamp-to-set-spectroscope/), “Your spectrograph has roughly the same resolution as the ALPY (R~500) and these lines are known to be reliable and give a very accurate calibration to better than 1A with the ALPY. I have attached a list of wavelengths of the 13 lines. They correspond to lines identified in the spectrum by Richard Walker using his DADOS with 200l/mm grating (R 900). If you identify as many of the lines in your spectrum as possible and make a 3rd order fit, any wrongly identified lines will immediately stand out as they will have larger errors.”
Lines used by ISIS to calibrate ALPY
Here is my go at identifying emission lines on y RELCO Spectrum using the Atlas of Emission Lines 200 lines/mm spectrum.
My RELCO with my attempt at identifying lines:
I used the following spectrum from http://www.ursusmajor.ch/downloads/sques-relco-sc480-calibration-lines-5.0.pdf from which to identify above lines:
Today, I have had a go at calibrating the homemade RELCO Starter bulb calibration lamp I made against 12V compact fluorescent lamp bulb in order to determine the wavelengths of the main lines on the CCDSPEC spectrum of the RELCO bulb.
Download calibration files from analysis by clicking on link below – calibration files RELCO vs CFL CCDSPEC no telescope 30/9/2018:
Also look at https://stargazerslounge.com/topic/226911-neon-lamp-to-set-spectroscope/?tab=comments#comment-3521335 to find out what happened when I tried to compare the lines I identified below with the atlas of lines from http://www.ursusmajor.ch/downloads/sques-relco-sc480-calibration-lines-5.0.pdf – sadly they don’t seem to match!
RELCO Starter Bulb spectrum taken with CCDSPEC Spectrometer (below):
Spectrum of compact fluorescent light bulb taken with CCDSPEC (below):
Graphing both above spectra together:
Calibrating spectra of both RELCO and CFL using above two lines in RSPEC gives following calibrated spectra:
The following is my final labelled image showing main lines on RELCO starter bulb spectrum (below):
I have had a go at creating a polynomial equation generating Excel spreadsheet for spectrometer calibration which I attach to this post (this is my own creation).