External alignment with X-Ray Telescope (XRT) and EUV Imaging Spectrometer (EIS)

1. External alignment with X-Ray Telescope (XRT) and EUV Imaging Spectrometer (EIS) Y. Katsukawa (NAOJ) and SOT team SOT17 @ NAOJ

2. 5.UFSS-SA 6.UFSS-SB 11.OBU 7.NSAS 4.EIS 2.FPP 1.OTA1 3.XRT 9.IRU-B1 8.STT 10.IRU-B2 13.BUS-Y 12.BUS+X Satellite coordinate definition UFSS UFSS x: N-S y: E-W z: Slit wrt Solar-N EIS XRT EIS FPP OTA OTA Z Z z z X y Y X Y x SOT17 @ NAOJ

3. Alignment requirements The pointing axis of SOT represents the pointing axis of Solar-B; alignment of each instrument is performed so that its pointing axis to be coincide with that of the SOT. SOT17 @ NAOJ

4. Alignment cubes • Alignment cubes (cube mirrors) are attached to all the telescopes. Normal direction of the mirror surfaces represent the pointing direction of each telescope in the space-craft level test. The cubes are usually measured by a theodolite. • Offset angles of pointing direction was measured with respect to the alignment cubes in the instrument level tests. OTA alignment cube Pointing direction wrt the cubes SOT17 @ NAOJ Theodolite measurement

5. Z X SOT pointing measurement Tiltmeter Flat mirror • The field-of-view of SOT (OTA) is defined by the 2ndary field stop (2FS) located at the Gregorian focus. The FOV of 2FS is slightly larger than FPP NFI CCD. • The pointing axis of OTA is defined by the ray passing through the center of 2FS and the center of the entrance pupil. • The interferometer was aligned to the FOV center defined by 2FS in the WFE measurements. Tilt of the reference flat mirror provides the pointing direction of OTA. Alignment cube Theodolite 2ndary Field Stop Interferometer SOT17 @ NAOJ

6. Z X OTA – FPP alignment check on S/C • A beam splitter was inserted between OTA and FPP. The theodolite was aligned to 2FS of OTA, and provides a beam into FPP. • The crosshair of the theodolite was well located at the center of CCD (better than 4” on the Sun). FPP Optical Bench CCD 2ndary field stop collimator lens unit Beam splitter reimaging lens theodolite SOT17 @ NAOJ

7. Telescope alignment • Each telescope is mounted to the optical bench unit (OBU) by three mounting legs. • Tilt of the telescopes was aligned to OTA by adjusting lengths of the mounting legs. • When the adjustment, we used a telescope template which represents mechanical I/F of each telescope. Finally alignment was confirmed by the actual telescopes. FPP template XRT template FPP template EIS template SOT17 @ NAOJ

8. Alignment cube measurements • We have measured the telescope alignment cubes in the integration, before and after the S/C vibration test. SOT17 @ NAOJ

9. Summary • The measurement accuracy (repeatability) is better than 20” in the spacecraft-level measurements. • We have measured pointing alignment among SOT, XRT, EIS, and the sun-sensor several times, and the offsets are less than 1 arcmin for all the telescopes. • The final alignment measurement will be carried out before delivery to Uchinoura. SOT17 @ NAOJ