Reference Miles-star finder

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Reference Miles-star finder

Postby Paolo Berardi » Wed Oct 01, 2014 7:26 pm

Hi all, Marco Leonardi and I just upgraded our Excel spreadsheet used to browse the Miles spectral library. The purpose is to facilitate the selection of suitable reference stars for observing sessions. Also François T developed, among a series of excellent tools, a similar spreadsheet. To improve our tool we wanted to implement some features which we consider useful during observation. In particularly, by adding some VBA code, the spreadsheet calculates altitude, azimuth, parallactic angle and air mass for each Miles star. Now the data are compared with the same referred to observed target and the observer can get a list of suitable stars located at similar altitude above horizon, the requirement to compensate for the atmospheric extinction. Miles stars are filtered by means of some criteria.

Image

The observer just needs to input geographic coordinates, local time (with a current time “NOW” button option) and observed target RA/Dec. The latter can be provided by editing single fields or by means a Simbad formatted string (copy/paste from Simbad webpage). Beside the use of “NOW” button the observer can also plan the observation session by imputing the foreseen observation time.

When the above listed fields are filled (note UT time is calculated using time zone and DST extracted from PC setting), the observer can read the target altitude, azimuth, parallactic angle and air mass in the output area.

Pressing "FIND STARS" button the observer obtains a list of Miles stars that meet the following requirements:

- above the horizons at preset time
- altitude difference respect to the target lower than preset value
- T eff within the preset range values (to exclude the cooler stars, which are not very suitable for response calculation – roughly with T eff > 7000 you can filter A/B/O classes stars).

Altitude difference means that if you put, for example, “Limit delta altitude” to 5 degree and target is at 50 degree above horizon, output list will include all Miles stars having altitude in the range 45 - 55 degree.

Image

Output list includes:

- main data for the stars (columns B to J)
- absolute altitude difference respect to the target (the sort key)
- angular distance from the target
- parallactic angle difference respect to the target
- altitude
- azimuth
- air mass (with Pickering 2002 interpolative formula)

Parallactic angle difference would help to avoid photometric distortions for narrow slit operations while observing far from the zenith. Also angular distance provide a similar information, making it clear if the Miles star is located in a distant area of the sky respect to the target (an important parameter in case of non-uniform sky condition). Finally, a practical purpose for those who use german mounts: stars with azimuth value colored in red may require a meridian-flip to observe them (they are located on the opposite east-west side respect to the target).

If the observer wants to see the spectrum of a Miles star in the output list, he/she can select any cell on Miles star row and press "View spectrum" button. If needed, the observer can go back to "Setup" tab to perform other search.

Image

We know the main problem in distributing spreasheets containing macros (like this) is the possibility that it could not run, besides any possible code writing errors, for substantial differences between OS and MS Excel versions (i.e. objects property syntax) and country settings. We tested it on italian OS (XP, Win 7, Win 8) and MS Excel 2003, 2010 and 2013. To reduce potential issue we provide both 32 and 64 bit versions because some support libraries need the specific mode (note that 32 and 64 bit are referred to MS Excel, you can have 64 bit OS and 32 bit Excel, in this case you should use the 32 bit version). Anyway, we recommend a few things to allow proper operations:

- you must allow macros execution:
Excel 2010/2013: File->Options->Trust Center-> Trust Center settings->Macro Setting. Choose Disable all macros with notification (macros are disabled but it will ask your permission each time before running a macro) or Enable all macros (low security)
Excel 2003: Tools->Macro->Security, choose Medium Security (macros are disabled but it will ask your permission each time before running a macro) or Low Security
- do not insert/delete any row/column
- do not modify any cells content except in the input green area

We are already using this tool and felt it is a good companion during our observing sessions. We would like to share hoping it might be in some way useful also to other people.

MS Excel Spreadsheet (all versions, 32 and 64 bit, 3 Mb):
http://quasar.teoth.it/html/varie/MILES_SEARCH_V1.zip

Miles spectral database (34 Mb):
http://quasar.teoth.it/html/varie/MILES_OBS.zip

Installation:

- Extract MILES_SEARCH_V1.zip in any place with folder structures option enabled. MILES_SEARCH_V1 folder should contain:

Image

- Extract files s0001-s0985 (file extension .test.dat) from MILES_OBS.zip in the empty folder MILES_OBS. Open the spreadsheet (the version you can use).

Note: if you already have installed the old SPEC_VIEW_V2 package (Miles spectra browser), you can download only spreadsheets. Just put them in the main folder along with the other.

Please feel free to contact us if something above is not clear. Also if you find any bug!

Paolo and Marco
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Re: Reference Miles-star finder

Postby Ken Harrison » Wed Oct 01, 2014 10:54 pm

Great stuff guys!
Your efforts are well appreciated. It will be a very useful spread sheet to all amateurs.
(A couple of comments: Column H isn't wide enough to show the time format, and you have to enter "-S" and "-E" in the location box not the usual "-" or "+" ;-) )
"Astronomical Spectroscopy - The Final Frontier" - to boldly go where few amateurs have gone before....
"Imaging Sunlight - Using a digital Spectroheliograph" - Springer
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Re: Reference Miles-star finder

Postby Paolo Berardi » Thu Oct 02, 2014 6:21 am

Ken, thank you very much for your kind comment! We expected a different formatting depending on country and personal settings, I hope excel use it's familiar enough for people. I suggest to enlarge the single column containing the date (or reformat the date) and save again the spreadsheet.

These are valid location approx. coordinates:

London:
Image

Paris:
Image

Melbourne:
Image

Los Angeles:
Image

All the best!
Paolo
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Re: Reference Miles-star finder

Postby Ken Harrison » Thu Oct 02, 2014 4:30 pm

Paolo,
I find I need to type "-"/"+" then press the enter key to get the signs to go into the cells.
"Astronomical Spectroscopy - The Final Frontier" - to boldly go where few amateurs have gone before....
"Imaging Sunlight - Using a digital Spectroheliograph" - Springer
http://www.astronomicalspectroscopy.com
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Location: St Leonards, Australia

Re: Reference Miles-star finder

Postby Paolo Berardi » Thu Oct 02, 2014 6:20 pm

It's correct Ken. This is the usual method to enter the +/- character in a cell. Sorry I didn't mention before. The sign seemed to us a "normal" indicator but if it's uncomfortable we can change with letters S, N, W, E (more logic! And with letters you can use also arrows in addition to [enter] key to enter data).

Paolo
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Re: Reference Miles-star finder

Postby Ken Harrison » Thu Oct 02, 2014 9:37 pm

I think the +/- sign is "more normal"
I just didn't think it through when entering the sign and moving to the next cell...
I wouldn't change it.
Thanks.
"Astronomical Spectroscopy - The Final Frontier" - to boldly go where few amateurs have gone before....
"Imaging Sunlight - Using a digital Spectroheliograph" - Springer
http://www.astronomicalspectroscopy.com
Ken Harrison
 
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Location: St Leonards, Australia

Re: Reference Miles-star finder

Postby Paolo Berardi » Sun Oct 05, 2014 10:14 am

Following the suggestion of Bernard Heathcote (on Yahoo group), we have added the ability to sort the output list according to specific fields. For this purpose you find a series of small buttons above each column name:

Image

Was also added a field that shows the absolute difference of air mass values between target and reference star.

The updated version v1.1 (requires the Miles spectral database, see above):

http://quasar.teoth.it/html/varie/MILES_SEARCH_V1_1.zip

Paolo
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Re: Reference Miles-star finder

Postby Paul Luckas » Thu Oct 09, 2014 5:22 am

Hi Paulo and Marco,

Thanks for providing such a great tool. It's great not to have to re-invent the wheel - as your spreadsheet works brilliantly.

Much appreciated,

Paul
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Re: Reference Miles-star finder

Postby Paolo Berardi » Sun Oct 12, 2014 10:36 am

Your welcome Paul, we thank you for the kind comment!

If you use ISIS, like us, you might find useful to know which stars are included in the internal database (in DB there is a subset of Miles library).

The 1.2 version is identical to 1.1 except for an asterisk after HD name in case of stars NOT included in ISIS database.

Image

http://quasar.teoth.it/html/varie/MILES_SEARCH_V1_2.zip
(requires the Miles spectral database, see above)

Clear sky!
Paolo and Marco
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Re: Reference Miles-star finder

Postby Robin Leadbeater » Thu Jan 22, 2015 2:37 pm

Would it be useful to add a link to this spreadsheet and also Francois Teyssier's spreadsheet which includes other low extinction hot stars
http://www.astronomie-amateur.fr/Docume ... inder.xlsm
to the ARAS website ?

Robin
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