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TILT

Purpose: To evaluate the scattered solar X-ray background contamination using the scale factors fitted by program RATE_FIT. There are three parameters which are evaluated: the total number of contaminating counts in each band, the gradient of the counts across the image, and the rotation angle of that gradient. The gradient is assumed to be linear.

File Input:
1) Observation data set fits files - xxx_ATTITUDE.FITS,
xxx_EVENTRATES.FITS, and xxx_ORBIT.FITS for German data,
xxx_ATTITUDE1.FITS, xxx_EVENTRATES.FITS, and xxx_ORBIT.FITS for US data, xxx_ANC.FITS for RDF data.
2) Other fixed input - valid_times.dat modified as desired from the output of program VALID_TIMES. This must be the same time selection as used with the programs CAST_DATA, CAST_EXP, CAST_PART, and LTE. WINDOW.DAT window transmission, EFF_AREA.DAT on-axis effective areas, GAS_EFF.DAT PSPC counter gas stopping efficiencies, DRM.FITS detector response matrix, SG.DAT solar and geophysical data, and RSPECTRA.FITS Raymond and Smith (1991 vintage) thermal spectra.

Interactive Input:
1) Observation control - the eight or fewer character string listed xxx
2) Data format control - 1 for German data, 2 for US data, 3 for RDF data.
3) Mode control - 1 for simple treatment, 2 for more complete treatment. The simple treatment assumes that the situation is optically thin, the more complete treatment uses a nearly complete radiative transfer approach.
4) Time offset and scale factors - T0, IS01, IS11, IS02, IS12, IS04, and IS14 results of RATE_FIT. (IS01 and IS11 are the fitted values for IS0 and IS1 for band R1. Similarly, IS02, IS12, IS04, and IS14 are the fitted values for IS0 and IS1 for bands R2 and R4, respectively.) At this time, TILT ignores band R3. The values IS01 and IS11 are used to scale the values for the R1 or R1L bands, IS02 and IS12 are used to scale the values for the R2 band, while IS04 and IS14 are used to scale the values for the R4 through R7 bands. Bands R4-R7 are not allowed to vary independently since essentially all the counts originate as oxygen K emission and so counts in the higher bands are just pulse-height spillover from 0.53 keV. NOTE: Even if the fitted parameters IS0 and IS1 are zero for a given band (R1, R2, or R4), a non-zero value for IS0 must be input for TILT and the results for the given band just ignored. Otherwise, TILT will crash on a divide by zero. The same holds true if certain bands are not being processed. In order to not produce too unreasonable a value for the total number of counts (which is used as an input to the program FIT_AP) a value for IS0 of 0.1 (to replace an otherwise zero input) is acceptable. (The results of FIT_AP are not particularly sensitive to the value for the total number of scattered solar X-ray counts, as long as it is at least roughly, order of magnitude, accurate.)
5) Temperature and scale factor for first component - the intrinsic solar spectrum is modelled as two-component thermal plasma emission, in this case, Raymond and Smith (1977) with the 1991 computer code update. The program requests the log of the temperature and the scale factor for each component. These temperatures and scale factors must be the same as those used above with the program AO.
6) Temperature and scale factor for second component - see 5)

Screen Output:
1) Contamination parameters - counts, rotation angles, and gradients for each band (except R3).