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
A 43140 ARK 564 340.664 29.7252026-01-01T12 0.0
D 00000 Cyg X-2 p08 326.188 38.3102026-01-06T18 1638.4
A 53140 ARK 564 340.664 29.7252026-01-09T06 852.0
D 00000 Cyg X-2 p07a 326.117 38.3402026-01-10T18 1572.9
A 63140 ARK 564 340.664 29.7252026-01-12T00 0.0
D 00000 Cyg X-2 p01a 326.176 38.3622026-01-15T18 1048.6
D 00000 Cyg X-2 e01 326.165 38.3322026-01-17T06 1769.4
D 00000 Cyg X-2 e02 326.213 38.2702026-01-18T12 2490.3
A 73140 ARK 564 340.664 29.7252026-01-19T12 1022.5
D 00000 Cyg X-2 p03a 326.227 38.3072026-01-22T12 2333.2
D 00000 Cyg X-2 e03 326.085 38.3682026-01-24T12 2827.8
A 83140 ARK 564 340.664 29.7252026-01-25T12 1569.7
D 00000 Cyg X-2 e04 326.132 38.2452026-01-28T00 2064.3
D 00000 Cyg X-2 e05 326.172 38.3892026-01-29T00 2558.9
D 00000 Cyg X-2 e06 326.068 38.2972026-01-30T00 3053.5
D 00000 Cyg X-2 e07 326.249 38.3502026-01-30T18 3548.1
L 13224 MRK 501 253.468 39.7602026-01-31T18 2525.8
L 13215 1E 1547.0-54 237.725 -54.3072026-02-02T18 599.8
D 00000 GX 349+2 256.435 -36.4172026-02-06T18 1729.8
L 23215 1E 1547.0-54 237.725 -54.3072026-02-08T18 0.0
L 23224 MRK 501 253.468 39.7602026-02-12T18 0.0
A 13003 LS I +61 303 40.132 61.2292026-02-14T18 0.0
A 03016 CRAB PULSAR 83.633 22.0142026-02-21T06 2271.2
L 33215 1E 1547.0-54 237.725 -54.3072026-02-22T18 345.2
L 33224 MRK 501 253.468 39.7602026-02-26T18 0.0
A 03016 CRAB PULSAR 83.633 22.0142026-02-28T18 2271.2
L 43215 1E 1547.0-54 237.725 -54.3072026-03-02T12 0.0
L 43224 MRK 501 253.468 39.7602026-03-10T06 0.0
A 13003 LS I +61 303 40.132 61.2292026-03-12T06 0.0
L 53215 1E 1547.0-54 237.725 -54.3072026-03-18T18 0.0
L 53224 MRK 501 253.468 39.7602026-03-25T12 0.0
A 03079 SS 433 E2 288.543 4.9372026-03-27T18 0.0
L 63224 MRK 501 253.468 39.7602026-04-07T12 0.0
A 03016 CRAB PULSAR 83.633 22.0142026-04-09T18 2271.2
A 03250 MRK 421 166.114 38.2092026-04-11T06 0.0
L 73224 MRK 501 253.468 39.7602026-04-22T00 0.0
A 23261 4U 1916-053 289.698 -5.2382026-04-24T00 0.0
L 83224 MRK 501 253.468 39.7602026-05-07T12 0.0
A 03079 SS 433 E2 288.543 4.9372026-05-09T18 0.0
L 93224 MRK 501 253.468 39.7602026-05-20T12 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 16, 2026 | Author/Curator: Mitzi Adams, mitzi.adams @ nasa.gov