Focas
Description
Focas (FOtometría Con AStrometrica), is a simple program that takes advantage of the extraordinary astrometric precission of Astrometrica, an excellent program developped by Herbert Raab, in an environment as comfortable as possible for the user, to produce quality photometric measures of asteroids and comets, the comet measures are adapted to the criteria stablished in the Cometas_Obs mailing list (10x10 and multibox), at the same time the program preserves the astrometry from Astrometrica.
History and revisions
17/12/2003 - First published version.
23/12/2003 - Modification in the way images are opened: Direct reading of Astrometrica data and more control over the images.
25/12/2003 - Correction of a bug in the image orientation.
01/01/2004 - More controls on the opening of astrometrica.log. The measures in the MPC reports are separated according to the used catalog for astrometry, they are sorted on the object's name and report’s e-mail delivery date.
02/01/2004 - To prevent the manual edition of reports from Track & Stack, the astrometry obtained in this manner is moved to the MPC report. On the window "Photometry Analysis", all the measured objects multi aperture magnitudes will be shown, though only these for comets will pass onto the report.
03/01/2004 - Before copying to the MPC report the measures coming from Track & Stack, a window will allow its selection. Two new buttons in the send e-mail report window allow the inspection of the data before sending it.
11/01/2004 - Track & Stack measures, of asteroids, will keep the magnitudes as measured with Astrometica. Fixed a bug where under certain circumstances non numbered asteroids where considered as comets.
13/01/2004 - Correction to adapt the program to a different astrometrica.log format, probably of an earlier version.
15/02/2004-b - From this release on, multi aperture measures are build only with the data selected in the graphical analysis window. The images containing only measures of asteroids can be processed with any catalog. Fixed a bug which caused, in some cases, non-sense high magnitudes for faint objects. Fixed a bug causing eventual duplication of some Track & Stack measures and eventual deletion of others.
26/02/2004 - English version. Correction of some minor bugs.
07/03/2004 - The measures are always sent in the e-mail body, and attached optionally.
12/06/2004 - Making of variable stars report in VSNET format.
23/03/2005 - Sending of variable stars reports via internet.
01/09/2005
- Correction of multibox measures abnormally bright due to the presence
of
near stars. Improvements in calculation of the sky background, in case
of comets, with the
object to reduce the dispersion of measures. Improvements in selection
of comparison stars.
Download
Installation
As simple as copying the executable. The first time, the program will open a window to allow us to select the language:
Next, we should inform the program about the Astrometrica location, to that purpose a window will open asking the location of the executable: astrometrica.exe.
All the neccesary data will be extracted from the Astrometrica configuration. The essential data are those that must appear in the MPC report and the maximum allowed error for the photometric reduction. A sensible value allowing comparison stars enough with an acceptable deviation, is 0.3 magnitudes.
Operation
To understand the way FOCAS extracts the Astrometrica data it is convenient to introduce the term "session". A session is the work done with Astrometrica since the reduction of an image or group of images is started till another session is started or the program is closed. Most often it consists in calibrating the images and identifying the objects to be measured.
The first step is to carry out all the measures of the images under study with Astrometrica. Focas reads the Astrometrica log so that the data are available since the measures are done until the log is deleted
The data corresponding to each image are those from the last session in which the image was reduced. The Astrometrica log may have data from more than one session , only the data from the last session will be valid. Some details must be taken into account:
More than five images: Astrometrica is not able to process more than five images at a time. If we have to measure more, corresponding to the same field, they have to be opened in two or more sessions.
Track & Stack: The data generated by Astrometrica using this sort of analysis are not usable by Focas because they do not relate to any particular image. However, the astrometry generated by this system, together with the asteroid photometry, will be moved into the MPC report.
About the catalogs: Even though Astrometrica supports various catalogs: UCAC 2, USNO-B1.0 and USNO-A 2.0, photometry can only be done with USNO-A 2.0. UCAC 2 is not adequate for this sort of measures because the magnitudes of its stars are only valid for identification purposes, the validity of USNO-B 1.0 has been questioned. However these two catalogs are an excellent source of data for the astrometric reductions due to its great accuracy and information on the proper movements of the stars. It is possible to combine its astrometry with the USNO-A 2.0 photometry. It suffices to do two measuring sessions with Astrometrica. The first one with the astrometric catalogs UCAC 2 or USNO-B 1.0, and the second with the photometric catalog, USNO-A 2.0. Once both finished, the data obtained can be processed with Focas. Focas will not recognise the photometry from the first session as valid, but it will keep the astrometry to include it when processing the second (photometric) session, all this in an automatic fashion.
About Astrometrica: Focas has been tested with the version 4.3.2.346. It is possible that with previous versions, the formats of the files differ producing errors. In this case please contact me and I'll try to find a solution, though the most convenient is to play always with the latest version.
Several objets: When there are various moving objects in the images, it's enough to select them all in Astrometrica in order to process them later on with Focas.
In summary: The only condition for Focas to be able to process one image is to have it previously processed with Astrometrica. When an image has been treated various times, the conditions and results from the last one will be valid. If we want to do astrometry with UCAC 2 or USNO-B 1.0, first we have to process the images with one of these catalogs and later on with USNO-A 2.0, before working with Focas.
Getting the measures
Once the images have been reduced and the objects measured in Astrometrica we can process them in Focas. If at the moment of opening Focas there are stored measures, a window will open warning about it and allowing the inspection and eventual deletion of them.
Below is the main window of the program.
Clicking on the "Images" button, the program will analyse the Astrometrica's log, extracting the data from the different sessions and showing them on the screen. In the case it finds an error situation it will inform about it, when not in error it will display information on the catalogs used for astrometry and photometry.
Next, we should select the images to process. With the "Select valid lines" button all the lines will be marked. We could individually select any of them by following the standard windows convention, one by one with "Ctrl + Left click" or in groups with "Shift+ Left click". The images with errors are not selectable.
Once the images have been selected, the "Process" button will be enabled allowing the start of the photometric measures. A bar on the form shows the progress of the task. During the process, the program does a photometric calibration of each image using all the stars, then it will repeat discarding those with errors greater than the specified threshold in the Astrometrica's configuration, finally it computes the magnitudes for all the objects on the image combining it with the astrometry from Astrometrica to generate the different reports.
Once finished, for each object, the program will show the results on a window.
To save the measures with destination to the MPC report, we'll select with "Ctrl + Left Click" the measures we want from the bottom table, we should also indicate whether the measure is for the comet's total or for the most brilliant part of the coma, according to the MPC criteria.
Clicking on the "Save to report" button the selected measures will be saved.
Finally, when there is astrometry coming from Track & Stack, a window will allow its selection for copy to the MPC report.
Once the process is completed, a window will propose the deletion of the Astrometrica log.
MPC and Multibox reports
The options for the maintenance of these reports, in the main menu, allow the manual edition of the measures (for the correction of potential errors), the generation and archiving of the reports and its deletion..
Internet
Since version (01/01/2003) on, the program has a facility to send the reports by e-mail. It's possible to select up to four different destinations each with its particular setup.
E-mail setup:
First thing, you should access the set up window by clicking on the "E-mail setup..." button to key in the necessary values for the outgoing mail server, which are the same settings of our usual e-mail program.
Next we can define the criteria for report sending in four equal sections.
We should specify an e-mail address and the mail's subject. With the "Mail text..." button an edition window will open where we can key it in, with the radio control "Include signature" we will allow or not its inclusion, finally we will select the reports that we want to send and the mode in which they will appear in the mail: as attachments or included in the body. If we have specified a text for e-mail, the corresponding button will be in bold. All the data but the mail's text will be kept for subsequent use.
Important:
The criteria for an e-mail to be sent is that there's an e-mail address and that the radio "Active" is selected. By default these radios are always marked. If at any moment we want not to send some mails and we don't want to clear the mail address details it's enough to de-select the radio and the mail will not be sent..
Sending mail:
Of course, first thing, we must have the internet connection alive. Next we click on the "Send..." button and a window will open with information on the mails to be sent.
Clicking on "Accept", the program will connect to the server and send the mails, showing on the same window the results of the communication.
Doubts, questions, sugestions and ... collaboration
We Invite all the users of this program to subscribe to the discussion mailing list Cometas-Obs es.groups.yahoo.com/group/Cometas_Obs, where you can find technical support and information on future program updates.
At the same time, the observations may also be sent to this list in order to collaborate with other amateurs in the maintenance of our database of cometary observations www.astrosurf.com/cometas-obs.
Gratefulness
To Ramón Naves and Esteban Reina for their collaboration in the program's development with their ideas, suggestions and patience during the testing. To Juan Lacruz for the translation of this document.