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 00 CYG X-1 299.590 35.2022026-06-06T15 1592.0
A 03175 1ES 1959+650 299.999 65.1492026-06-08T18 622.0
A 13260 CEN X-3 170.313 -60.6242026-06-14T06 664.7
L 13224 MRK 501 253.468 39.7602026-06-18T15 123.7
A 33239 MCG-06-30-15 203.974 -34.2962026-06-20T18 0.0
C 13089 1E 1145.1-61 176.869 -61.9542026-06-22T06 0.0
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 00 Her X-1 254.458 35.3422026-07-02T03 0.0
D 00 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 3.6
A 13001 4U 0115+63 19.633 63.7432026-07-16T15 1698.6
C 23089 1E 1145.1-61 176.869 -61.9542026-07-21T00 1103.7
A 23001 4U 0115+63 19.633 63.7432026-07-23T09 2258.1
L 33215 1E 1547.0-54 237.725 -54.3072026-07-29T12 1724.5
L 43224 MRK 501 253.468 39.7602026-07-31T12 1183.5
L 43215 1E 1547.0-54 237.725 -54.3072026-08-02T12 0.0
L 53224 MRK 501 253.468 39.7602026-08-09T21 0.0
NOTES:
Plan covers time up to 2026 Aug.
ToOs will cause planned times to shift around.
+ NASA Privacy, Security, Notices | Last Updated: July 10, 2026 | Author/Curator: Mitzi Adams, mitzi.adams @ nasa.gov