For Scientists: The Long-Term Plan

This is the current Long-Term Plan (LTP) for IXPE. The Science Advisory Team requested that transient targets be added when and if they become bright. At such time, the LTP will be adjusted, attempting to minimize the impact on the overall plan; however, nothing is guaranteed.

IXPE is telemetry limited for bright sources and this requires that observations be handled slightly differently from the way most X-ray missions operate. If IXPE is observing a bright source that could potentially fill on-board storage, we shall divide the observation into multiple segments.

COLUMNS:
P: can be A, C, L, D or T. A and C targets were assigned by peer review. T is a ToO and D is DDT time. L denotes a large project. If an A target is bumped due to a ToO, it will be replaced. If a C target is bumped, it will likely be dropped from the plan.

S: This is a segment number. If segment is zero, then the observation has not been segmented.

Pnum: This is the GO proposal number. If the observation is a DDT or a calibration, then this number will be zero.

Name: This is a common name for the target.

RA: Target RA in decimal degrees.

Dec: Target Dec in decimal degrees.

Start: The Year-Month-Day The date the observation is planned to begin. The digits after the T is the start hour, in UT, truncated to a 6 hr interval.

buffer: This is an estimate as to how much data will stll be on the spacecraft when the observation ends in MB. The on-board storage can hold just over 4500 MB and when planning we keep the usage below 4000 MB.

P S Pnum Name RA Dec Start buffer
D 00000 Cyg X-2 e04 326.125 38.2482026-01-28T00 1852.7
D 00000 Cyg X-2 e05 326.171 38.3892026-01-29T00 2347.3
D 00000 Cyg X-2 e06 326.069 38.2962026-01-30T00 2841.9
D 00000 Cyg X-2 e07 326.248 38.3512026-01-30T18 3336.5
L 13224 MRK 501 253.468 39.7602026-01-31T18 2314.2
L 13215 1E 1547.0-54 237.725 -54.3072026-02-02T18 1351.2
A 13252 GS 1354-64 209.541 -64.7352026-02-06T12 3853.5
A 13239 MCG-06-30-15 203.974 -34.2962026-02-09T00 2608.2
L 23224 MRK 501 253.468 39.7602026-02-11T12 1493.9
A 13003 LS I +61 303 40.132 61.2292026-02-13T12 0.0
A 03252 GS 1354-64 209.541 -64.7352026-02-18T06 1397.1
A 23003 LS I +61 303 40.132 61.2292026-02-20T18 423.2
A 23239 MCG-06-30-15 203.974 -34.2962026-02-22T12 0.0
L 33224 MRK 501 253.468 39.7602026-02-27T00 0.0
D 00000 GX 349+2 256.435 -36.4172026-03-01T06 1037.7
L 23215 1E 1547.0-54 237.725 -54.3072026-03-03T06 0.0
L 43224 MRK 501 253.468 39.7602026-03-10T06 0.0
A 23003 LS I +61 303 40.132 61.2292026-03-12T06 0.0
A 13261 4U 1916-053 289.698 -5.2382026-03-19T00 0.0
L 53224 MRK 501 253.468 39.7602026-03-24T06 0.0
A 23261 4U 1916-053 289.698 -5.2382026-03-26T12 0.0
L 33215 1E 1547.0-54 237.725 -54.3072026-04-01T00 0.0
L 13224 MRK 501 253.468 39.7602026-04-09T00 0.0
A 03250 MRK 421 166.114 38.2092026-04-11T00 0.0
A 33261 4U 1916-053 289.698 -5.2382026-04-21T18 0.0
L 23224 MRK 501 253.468 39.7602026-04-24T06 0.0
A 13079 SS 433 E2 288.543 4.9372026-04-26T06 0.0
L 33224 MRK 501 253.468 39.7602026-05-09T12 0.0
A 23079 SS 433 E2 288.543 4.9372026-05-11T12 0.0
NOTES:
Plan covers time up to 2026 May.
ToOs will cause planned times to shift around.
+ NASA Privacy, Security, Notices | Last Updated: January 31, 2026 | Author/Curator: Mitzi Adams, mitzi.adams @ nasa.gov