For Scientists: The Long-Term Plan

This is the current Long-Term Plan (LTP) for IXPE. IXPE is currently observing targets from GO Cycle 3. Category A targets are guaranteed to be observed, including the following A targets carried over from the previous cycle:

Prop Name RA Dec
2142 SS 433 287.9565 4.98272
The IXPE project expects to be able to observe ~50% of Category C targets. 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 3 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
C 13213 XB 1254-690 194.405 -69.2892026-05-29T15 0.0
L 53224 MRK 501 253.468 39.7602026-06-04T15 0.0
D 00000 CYG X-1 299.590 35.2022026-06-06T15 1778.0
A 03175 1ES 1959+650 299.999 65.1492026-06-08T18 1297.1
A 13260 CEN X-3 170.313 -60.6242026-06-14T06 1722.0
L 13224 MRK 501 253.468 39.7602026-06-18T15 1364.8
A 33239 MCG-06-30-15 203.974 -34.2962026-06-20T18 1076.2
C 13089 1E 1145.1-61 176.869 -61.9542026-06-22T06 697.6
A 43239 MCG-06-30-15 203.974 -34.2962026-06-24T18 0.0
L 23224 MRK 501 253.468 39.7602026-06-30T00 0.0
D 00000 Her X-1 254.458 35.3422026-07-02T03 0.0
D 00000 EP260628c 339.498 53.2392026-07-06T06 0.0
A 53239 MCG-06-30-15 203.974 -34.2962026-07-10T03 0.0
L 33224 MRK 501 253.468 39.7602026-07-14T03 0.0
A 23260 CEN X-3 170.313 -60.6242026-07-16T06 36.2
A 13001 4U 0115+63 19.633 63.7432026-07-16T15 2102.5
C 23089 1E 1145.1-61 176.869 -61.9542026-07-21T00 1723.9
A 23001 4U 0115+63 19.633 63.7432026-07-23T12 3401.6
L 33215 1E 1547.0-54 237.726 -54.3072026-07-29T15 3039.7
L 43224 MRK 501 253.468 39.7602026-07-31T12 2682.5
L 43215 1E 1547.0-54 237.726 -54.3072026-08-02T15 1307.4
L 53224 MRK 501 253.468 39.7602026-08-10T00 950.2
C 13090 GX 1+4 263.009 -24.7462026-08-12T03 99.5
A 03016 CRAB PULSAR 83.633 22.0152026-08-17T09 2687.7
C 33089 1E 1145.1-61 176.869 -61.9542026-08-19T00 2309.2
C 33234 FAIRALL 51 281.225 -62.3652026-08-21T09 1314.5
L 13224 MRK 501 253.468 39.7602026-08-26T18 957.3
NOTES:
Plan covers time up to 2026 Aug.
ToOs will cause planned times to shift around.
+ NASA Privacy, Security, Notices | Last Updated: July 23, 2026 | Author/Curator: Mitzi Adams, mitzi.adams @ nasa.gov