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
L 13224 MRK 501 253.468 39.7602026-01-31T18 437.2
L 13215 1E 1547.0-54 237.725 -54.3072026-02-02T18 0.0
D 13252 GS 1354-64 209.541 -64.7352026-02-06T12 2088.2
A 13239 MCG-06-30-15 203.974 -34.2962026-02-09T00 1459.4
L 23224 MRK 501 253.468 39.7602026-02-11T12 896.7
A 13003 LS I +61 303 40.132 61.2292026-02-13T12 0.0
D 00000 GX 349+2 256.435 -36.4172026-02-18T00 2283.4
A 23003 LS I +61 303 40.132 61.2292026-02-19T18 2108.0
A 23239 MCG-06-30-15 203.974 -34.2962026-02-21T12 1514.1
L 33224 MRK 501 253.468 39.7602026-02-27T18 1318.9
D 00000 GX 349+2 256.435 -36.4172026-03-02T00 3602.3
L 23215 1E 1547.0-54 237.725 -54.3072026-03-03T12 2917.9
L 43224 MRK 501 253.468 39.7602026-03-10T12 2744.5
A 23003 LS I +61 303 40.132 61.2292026-03-12T12 2108.4
A 13261 4U 1916-053 289.698 -5.2382026-03-19T00 1653.6
L 53224 MRK 501 253.468 39.7602026-03-24T12 1480.2
A 23261 4U 1916-053 289.698 -5.2382026-03-26T12 1007.2
L 33215 1E 1547.0-54 237.725 -54.3072026-04-01T06 227.8
L 13224 MRK 501 253.468 39.7602026-04-09T06 54.4
A 03250 MRK 421 166.114 38.2092026-04-11T06 0.0
A 33261 4U 1916-053 289.698 -5.2382026-04-22T00 0.0
L 23224 MRK 501 253.468 39.7602026-04-24T12 0.0
A 13079 SS 433 E2 288.543 4.9372026-04-26T12 0.0
L 33224 MRK 501 253.468 39.7602026-05-09T12 0.0
A 23079 SS 433 E2 288.543 4.9372026-05-11T18 0.0
NOTES:
Plan covers time up to 2026 May.
ToOs will cause planned times to shift around.
+ NASA Privacy, Security, Notices | Last Updated: February 05, 2026 | Author/Curator: Mitzi Adams, mitzi.adams @ nasa.gov