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Pointing Models for 26 West and East

Pointing Models for 26 West and East. Anna Castelaz Summer 2003. Introduction. Why do we need pointing models? Which models did I develop? East, 1420 MHz East, 4.8 GHz West, 4.8 GHz Revisions on 1420 MHz for West. Procedure.

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Pointing Models for 26 West and East

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  1. Pointing Models for 26 West and East Anna Castelaz Summer 2003

  2. Introduction • Why do we need pointing models? • Which models did I develop? • East, 1420 MHz • East, 4.8 GHz • West, 4.8 GHz • Revisions on 1420 MHz for West

  3. Procedure • To make a model, I would first have to point the telescope at point sources throughout the sky. SAMPLE POINT: 0022+5544 • There were several calculations necessary to make the data easier to work with. I precessed the coordinates to the current catalog positions, using the site http://fuse.pha.jhu.edu/support/tools/precess.html to do so. • Then these coordinates and the peaked coordinates, in RA and DEC, were changed into decimal notation. SAMPLE POINT:

  4. The coordinates had to be changed into degrees: • The formulae on the left changed the data into unit vectors and the ones on the right compensate for latitude • the latittute at PARI is 35.2049 degrees, or .6144 radians. • After taking latitude into account, I could finish converting into degrees: SAMPLE POINT:

  5. Now I could calculate errors. • The EMAJ and EMIN errors and the total error: SAMPLE POINT: • I collected approximately 35 points for the models for 26 East at 1420 MHz and 26 West at 4.8 GHz.. There were 51 points from the model for West in 1420 last year, and I was only able to collect 15 points for East at 4.8. I ran all of the points through the calculations.

  6. Results • For each model there were four graphs. They were combinations of either the observed positions and the difference between the catalog and observed positions; or TMAJ vs. EMAJ, TMAJ vs. EMIN, TMIN vs. EMAJ, and TMIN vs. EMIN. • To save space, I have plotted all four on the same graph for each model Graph for 1420 MHz on 26 East

  7. Graph for 4.8 GHz on 26 West

  8. Graph for east 4.8 on this page!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

  9. Graph for 1420 MHz on 26 West

  10. EMIN vs. TMAJ Curve = ME = elevation misalignment in arc sec Slope = MA = azimuth misalignment in arc sec EMIN vs. TMIN Curve = TFLX = tube flexure for minor axis Slope = SCLMIN = minor scale factor • These graphs are important because their slopes and curvatures are used as constants in the pointing model formulas. EMAJ vs. TMAJ Curve = TFLX = tube flexure for major axis Slope = SCLMIN = major scale factor EMAJ vs. TMIN Curve = CH = collimation Slope = NP = non- perpendicularity Constants not previously mentioned: MAJECC = eccentricity error amplitude MINOFF = eccentricity offset

  11. The Pointing Model Program • To run my data in the pointing model program, I created a *.pat file of the data. This was essentially a long column of entries including the current catalog RA and DEC, the observed RA and DEC, and the HA. • The program shows graphs and a list of the constants. It corrects its pointing by looping through the EMIN and EMAJ equations and the MajorEorror and MInorError equations. (For the EMIN and EMAJ equations, it uses: • and Comments

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