GRB 250309B/IceCube-250309A: Swift observation summary

Mission:	Fermi/GBM
GRB RA:	210.801°
GRB Dec:	-10.440°
GRB Err:	1.0 deg
T0:	2025-03-09 07:38:31 UT
Galactic:	330.19° +48.60°
Galactic N_H:	3.96× 10²⁰ cm^-2
Galactic E(B-V):	0.05149493

Sun distance:	136.29°
Sun angle:	9.25 [hr](West of Sun)
Moon distance:	100.75°
Visibility of this field.
First slew:	2025-03-09 10:57:39 UT
First observation:	2025-03-09 10:57:08 UT
First analysis:	UT

About tiled field analysis.

So far 28 fields have been scheduled for observations. Data are available and processed for 28 of these. The list gives the exposure time used in source detection. If any individual sources were selected for follow-up observations, the source detection is not repeated for the follow up observations and the table below is not updated.

21786 — 619 s of cleaned data taken between 2025-03-09 10:57:37 and 2025-03-09 11:10:35
21788 — 406 s of cleaned data taken between 2025-03-09 11:10:37 and 2025-03-09 11:18:05
21789 — 270 s of cleaned data taken between 2025-03-09 15:38:52 and 2025-03-09 15:46:19
21790 — 228 s of cleaned data taken between 2025-03-09 16:00:08 and 2025-03-09 16:06:42
21791 — 253 s of cleaned data taken between 2025-03-09 12:31:07 and 2025-03-09 12:38:15
21792 — 293 s of cleaned data taken between 2025-03-09 16:06:54 and 2025-03-09 16:12:12
21795 — 280 s of cleaned data taken between 2025-03-09 17:12:40 and 2025-03-09 17:21:35
21796 — 782 s of cleaned data taken between 2025-03-09 11:18:06 and 2025-03-09 11:31:37
21797 — 283 s of cleaned data taken between 2025-03-09 17:21:38 and 2025-03-09 17:27:00
21798 — 270 s of cleaned data taken between 2025-03-09 18:46:51 and 2025-03-09 18:55:22
21799 — 313 s of cleaned data taken between 2025-03-09 14:05:07 and 2025-03-09 14:15:21
21800 — 238 s of cleaned data taken between 2025-03-09 14:15:24 and 2025-03-09 14:20:01
21801 — 293 s of cleaned data taken between 2025-03-09 14:20:06 and 2025-03-09 14:25:27
21802 — 293 s of cleaned data taken between 2025-03-09 14:25:31 and 2025-03-09 14:30:49
21803 — 290 s of cleaned data taken between 2025-03-09 14:30:52 and 2025-03-09 14:36:11
21804 — 290 s of cleaned data taken between 2025-03-09 14:36:13 and 2025-03-09 14:41:32
21805 — 285 s of cleaned data taken between 2025-03-09 18:55:25 and 2025-03-09 19:00:48
21806 — 135 s of cleaned data taken between 2025-03-09 12:41:14 and 2025-03-09 12:46:35
21807 — 263 s of cleaned data taken between 2025-03-09 12:46:37 and 2025-03-09 12:51:27
21808 — 842 s of cleaned data taken between 2025-03-09 12:51:31 and 2025-03-09 13:06:00
21809 — 285 s of cleaned data taken between 2025-03-09 19:00:51 and 2025-03-09 19:06:10
21810 — 273 s of cleaned data taken between 2025-03-10 01:02:02 and 2025-03-10 01:10:29
21811 — 3.8 ks of cleaned data taken between 2025-03-10 01:10:33 and 2025-03-10 03:09:19
21812 — 413 s of cleaned data taken between 2025-03-10 03:09:23 and 2025-03-10 03:16:43
21813 — 213 s of cleaned data taken between 2025-03-10 05:44:44 and 2025-03-10 05:51:14
21814 — 203 s of cleaned data taken between 2025-03-10 07:19:01 and 2025-03-10 07:24:11
21815 — 295 s of cleaned data taken between 2025-03-10 08:51:39 and 2025-03-10 09:00:10
21816 — 8.2 ks of cleaned data taken between 2025-03-09 20:24:40 and 2025-03-10 21:25:29

An additional 1 field has also been used for follow up observations. These data are not searched for sources, but are used to update the light curves etc of any sources already found.

Probable afterglow details

A source was found which matches the afterglow criteria.

#	RA (J2000)	Dec (J2000)	Err₉₀¹	Detection Flag²	Dist from Fermi/GBM pos	Exposure	Notes	Vizier
15 [details]	14h 03m 12.33s210.80138°	-08° 30′ 10.9″-8.50304°	2.8′′	Good	1.9°	8.2 ks	The source is 3.4-σ above the LSXPS limit.
Mean XRT rate: 4.3 (±0.4) ×10^-2 ct s^-1 Peak XRT rate: 8.4 (±2.2) ×10^-2 ct s^-1 RASS PSPC 3-σ upper limit: 0.02 ct s^-1 (XRT equiv count-rate) Mean XRT flux: 1.71 (±0.14) ×10^-12 erg cm^-1s^-1 Peak XRT flux: 3.4 (±0.9) ×10^-12 erg cm^-1s^-1 Products: Light curve \| Spectrum \| Enhanced position

¹ Radius, 90% confidence.
² Indicates how likely the source is to be real. See the 1SXPS documentation.
^* The position was enhanced using astrometry derived from the Swift UVOT.
^† The position was astrometrically corrected using the XRT sources and the 2MASS catalogue.

Find an upper limit.

Sources found so far

So far 28 sources have been found in the XRT data. 7 sources match catalogued sources.

#	RA (J2000)	Dec (J2000)	Err₉₀¹	Detection Flag²	Dist from Fermi/GBM pos	Exposure	Notes
1 [details]	14h 02m 57.40s210.73916°	-10° 51′ 50.9″-10.86415°	6.9′′	Good	25.7′	2.7 ks
Mean XRT rate: 9.1 (+3.8, -2.8) ×10^-3 ct s^-1 Peak XRT rate: 1.2 (+0.6, -0.5) ×10^-2 ct s^-1 RASS PSPC 3-σ upper limit: 0.10 ct s^-1 (XRT equiv count-rate) Mean XRT flux: 5.8 (+2.4, -1.8) ×10^-13 erg cm^-1s^-1 Peak XRT flux: 7 (+4, -3) ×10^-13 erg cm^-1s^-1 Products: Spectrum
2 [details]	14h 01m 01.58s210.25660°	-11° 12′ 24.1″-11.20669°	5.7′′	Good	56.1′	135 s	Matches known X-ray source: 4XMM J140101.8-111223 (from XMM-NEWTON/XMMSSC), 3.7″ away. Matches SIMBAD source: LEDA 94236, 3.7″ away.
Mean XRT rate: 6.0 (+3.3, -2.4) ×10^-2 ct s^-1 Peak XRT rate: 6.0 (+3.3, -2.4) ×10^-2 ct s^-1 RASS PSPC 3-σ upper limit: 0.0×10⁰ ct s^-1 (XRT equiv count-rate) Mean XRT flux: 2.7 (+1.5, -1.1) ×10^-12 erg cm^-1s^-1 Peak XRT flux: 2.7 (+1.5, -1.1) ×10^-12 erg cm^-1s^-1 Products: Spectrum
3 [details]	14h 06m 52.13s211.71719°	-10° 28′ 09.7″-10.46936°	11.1′′	Good	54.1′	842 s
Mean XRT rate: 7 (+4, -3) ×10^-3 ct s^-1 Peak XRT rate: 7 (+4, -3) ×10^-3 ct s^-1 RASS PSPC 3-σ upper limit: 0.02 ct s^-1 (XRT equiv count-rate) Products: Spectrum
4 [details]	14h 04m 34.98s211.14573°	-10° 13′ 04.9″-10.21802°	5.5′′	Good	24.3′	228 s	Matches known X-ray source: 1RXS J140433.0-101242 (from ROSAT/RASSBSC), 35.2″ away.
Mean XRT rate: 5.1 (+2.0, -1.6) ×10^-2 ct s^-1 Peak XRT rate: 5.1 (+2.0, -1.6) ×10^-2 ct s^-1 RASS PSPC 3-σ upper limit: 0.0×10⁰ ct s^-1 (XRT equiv count-rate) Products: Spectrum \| Enhanced position
5 [details]	14h 02m 43.22s210.68007°	-09° 41′ 37.4″-9.69373°	6.4′′	Poor	45.3′	4.5 ks
Mean XRT rate: undetermined ct s^-1 Peak XRT rate: undetermined ct s^-1 RASS PSPC 3-σ upper limit: 0.02 ct s^-1 (XRT equiv count-rate)
6 [details]	14h 04m 03.17s211.01321°	-09° 32′ 05.2″-9.53477°	8.5′′	Poor	55.7′	2.0 ks
Mean XRT rate: undetermined ct s^-1 Peak XRT rate: undetermined ct s^-1 RASS PSPC 3-σ upper limit: 0.03 ct s^-1 (XRT equiv count-rate)
7 [details]	14h 02m 46.80s210.69501°	-09° 30′ 00.4″-9.50011°	5.2′′	Good	56.7′	3.8 ks
Mean XRT rate: 2.8 (+1.4, -1.1) ×10^-3 ct s^-1 Peak XRT rate: 2.8 (+1.4, -1.1) ×10^-3 ct s^-1 RASS PSPC 3-σ upper limit: 0.08 ct s^-1 (XRT equiv count-rate) Mean XRT flux: 5.1 (+2.6, -2.0) ×10^-13 erg cm^-1s^-1 Peak XRT flux: 5.1 (+2.6, -2.0) ×10^-13 erg cm^-1s^-1 Products: Spectrum
8 [details]	14h 02m 56.63s210.73594°	-09° 30′ 46.3″-9.51286°	5.8′′	Reasonable	55.8′	3.8 ks
Mean XRT rate: 2.5 (+1.4, -1.0) ×10^-3 ct s^-1 Peak XRT rate: 2.5 (+1.4, -1.0) ×10^-3 ct s^-1 RASS PSPC 3-σ upper limit: 33316.26 ct s^-1 (XRT equiv count-rate) Mean XRT flux: 3.4 (+1.8, -1.4) ×10^-10 erg cm^-1s^-1 Peak XRT flux: 3.4 (+1.8, -1.4) ×10^-10 erg cm^-1s^-1 Products: Spectrum
9 [details]	14h 03m 26.57s210.86070°	-09° 24′ 47.9″-9.41330°	5.8′′	Poor	1.0°	3.8 ks
Mean XRT rate: undetermined ct s^-1 Peak XRT rate: undetermined ct s^-1 RASS PSPC 3-σ upper limit: 0.0×10⁰ ct s^-1 (XRT equiv count-rate) Mean XRT flux: undetermined erg cm^-1s^-1 Peak XRT flux: undetermined erg cm^-1s^-1 Products: Spectrum
10 [details]	14h 02m 36.65s210.65270°	-09° 39′ 42.0″-9.66168°	7.2′′	Reasonable	47.5′	4.5 ks
Mean XRT rate: 2.5 (+1.6, -1.2) ×10^-3 ct s^-1 Peak XRT rate: 2.5 (+1.6, -1.2) ×10^-3 ct s^-1 RASS PSPC 3-σ upper limit: 0.03 ct s^-1 (XRT equiv count-rate) Mean XRT flux: 6.3 (+4.0, -2.9) ×10^-14 erg cm^-1s^-1 Peak XRT flux: 6.3 (+4.0, -2.9) ×10^-14 erg cm^-1s^-1 Products: Spectrum
11 [details]	14h 03m 25.95s210.85811°	-09° 40′ 49.2″-9.68034°	5.7′′	Reasonable	45.7′	3.8 ks
Mean XRT rate: undetermined ct s^-1 Peak XRT rate: undetermined ct s^-1 RASS PSPC 3-σ upper limit: 0.02 ct s^-1 (XRT equiv count-rate) Mean XRT flux: undetermined erg cm^-1s^-1 Peak XRT flux: undetermined erg cm^-1s^-1 Products: Spectrum
12 [details]	14h 03m 50.91s210.96213°	-09° 40′ 21.1″-9.67253°	6.3′′	Poor	47.0′	4.0 ks
Mean XRT rate: 2.3 (+1.3, -1.0) ×10^-3 ct s^-1 Peak XRT rate: 2.3 (+1.3, -1.0) ×10^-3 ct s^-1 RASS PSPC 3-σ upper limit: 0.04 ct s^-1 (XRT equiv count-rate) Mean XRT flux: 9 (+5, -4) ×10^-14 erg cm^-1s^-1 Peak XRT flux: 9 (+5, -4) ×10^-14 erg cm^-1s^-1 Products: Spectrum
13 [details]	14h 03m 30.71s210.87794°	-09° 26′ 53.7″-9.44825°	7.0′′	Poor	59.7′	3.8 ks
Mean XRT rate: undetermined ct s^-1 Peak XRT rate: undetermined ct s^-1 RASS PSPC 3-σ upper limit: 0.02 ct s^-1 (XRT equiv count-rate) Products: Spectrum
14 [details]	14h 03m 14.71s210.81128°	-09° 21′ 50.0″-9.36390°	6.0′′	Poor	1.1°	1.7 ks
Mean XRT rate: 8 (+4, -3) ×10^-3 ct s^-1 Peak XRT rate: 8 (+4, -3) ×10^-3 ct s^-1 RASS PSPC 3-σ upper limit: 0.02 ct s^-1 (XRT equiv count-rate) Products: Spectrum
15 [details]	14h 03m 12.33s210.80138°	-08° 30′ 10.9″-8.50304°	2.8′′	Good	1.9°	8.2 ks	The source is 3.4-σ above the LSXPS limit.
Mean XRT rate: 4.3 (±0.4) ×10^-2 ct s^-1 Peak XRT rate: 8.4 (±2.2) ×10^-2 ct s^-1 RASS PSPC 3-σ upper limit: 0.02 ct s^-1 (XRT equiv count-rate) Mean XRT flux: 1.71 (±0.14) ×10^-12 erg cm^-1s^-1 Peak XRT flux: 3.4 (±0.9) ×10^-12 erg cm^-1s^-1 Products: Light curve \| Spectrum \| Enhanced position
16 [details]	14h 03m 28.91s210.87046°	-08° 40′ 23.2″-8.67311°	2.6′′	Good	1.8°	8.2 ks	Matches known X-ray source: XMMSL3 J140328.8-084034 (from XMM-NEWTON/XMMSLEWCLN), 2.9″ away. Matches SIMBAD source: LEDA 3096319, 2.6″ away.
Mean XRT rate: 4.7 (±0.3) ×10^-2 ct s^-1 Peak XRT rate: 7.7 (±2.0) ×10^-2 ct s^-1 RASS PSPC 3-σ upper limit: 0.0×10⁰ ct s^-1 (XRT equiv count-rate) Mean XRT flux: 1.47 (±0.10) ×10^-12 erg cm^-1s^-1 Peak XRT flux: 2.4 (±0.6) ×10^-12 erg cm^-1s^-1 Products: Light curve \| Spectrum \| Enhanced position
17 [details]	14h 02m 45.34s210.68890°	-08° 21′ 24.4″-8.35678°	4.3′′	Good	2.1°	8.1 ks
Mean XRT rate: 5.0 (+1.2, -1.1) ×10^-3 ct s^-1 Peak XRT rate: 6.2 (±1.5) ×10^-3 ct s^-1 RASS PSPC 3-σ upper limit: 0.05 ct s^-1 (XRT equiv count-rate) Mean XRT flux: 9.9 (+2.3, -2.2) ×10^-14 erg cm^-1s^-1 Peak XRT flux: 1.22 (±0.30) ×10^-13 erg cm^-1s^-1 Products: Spectrum \| Enhanced position
18 [details]	14h 03m 16.69s210.81954°	-08° 23′ 21.5″-8.38929°	5.5′′	Reasonable	2.1°	8.2 ks
Mean XRT rate: 1.4 (+0.7, -0.5) ×10^-3 ct s^-1 Peak XRT rate: 1.4 (+0.7, -0.5) ×10^-3 ct s^-1 RASS PSPC 3-σ upper limit: 0.03 ct s^-1 (XRT equiv count-rate) Mean XRT flux: 4.6 (+2.2, -1.8) ×10^-14 erg cm^-1s^-1 Peak XRT flux: 4.6 (+2.2, -1.8) ×10^-14 erg cm^-1s^-1 Products: Spectrum
19 [details]	14h 03m 01.11s210.75463°	-08° 33′ 51.7″-8.56436°	6.2′′	Reasonable	1.9°	8.2 ks
Mean XRT rate: 2.2 (+0.7, -0.6) ×10^-3 ct s^-1 Peak XRT rate: 2.2 (+0.7, -0.6) ×10^-3 ct s^-1 RASS PSPC 3-σ upper limit: 0.03 ct s^-1 (XRT equiv count-rate) Mean XRT flux: 7.0 (+2.4, -2.0) ×10^-14 erg cm^-1s^-1 Peak XRT flux: 7.0 (+2.4, -2.0) ×10^-14 erg cm^-1s^-1 Products: Spectrum
20 [details]	14h 01m 35.50s210.39793°	-11° 07′ 58.6″-11.13295°	6.2′′	Poor	47.9′	431 s	Matches known X-ray source: 1WGA J1401.5-1107 (from ROSAT/WGACAT), 11.5″ away.
Mean XRT rate: 2.95 (+1.24, -0.98) ×10^-2 ct s^-1 Peak XRT rate: 2.95 (+1.24, -0.98) ×10^-2 ct s^-1 RASS PSPC 3-σ upper limit: 0.0×10⁰ ct s^-1 (XRT equiv count-rate)
21 [details]	14h 01m 33.55s210.38977°	-11° 07′ 09.0″-11.11917°	7.8′′	Poor	47.4′	135 s	Matches known X-ray source: 2E 1358.9-1053 (from EINSTEIN/EINSTEIN2E), 39.9″ away.
Mean XRT rate: 4.2 (+2.6, -1.9) ×10^-2 ct s^-1 Peak XRT rate: 4.2 (+2.6, -1.9) ×10^-2 ct s^-1 RASS PSPC 3-σ upper limit: 0.0×10⁰ ct s^-1 (XRT equiv count-rate)
22 [details]	14h 02m 29.22s210.62173°	-08° 28′ 15.3″-8.47093°	6.8′′	Good	2.0°	8.2 ks
Mean XRT rate: 4.4 (±1.1) ×10^-3 ct s^-1 Peak XRT rate: 4.4 (±1.1) ×10^-3 ct s^-1 RASS PSPC 3-σ upper limit: 0.04 ct s^-1 (XRT equiv count-rate) Mean XRT flux: 1.6 (±0.4) ×10^-13 erg cm^-1s^-1 Peak XRT flux: 1.6 (±0.4) ×10^-13 erg cm^-1s^-1 Products: Spectrum \| Enhanced position
23 [details]	14h 03m 16.35s210.81812°	-08° 19′ 24.0″-8.32332°	5.3′′	Good	2.1°	8.2 ks	Matches SIMBAD source: Gaia DR3 3616160191748090880, 0.1″ away.
Mean XRT rate: 2.5 (+0.9, -0.7) ×10^-3 ct s^-1 Peak XRT rate: 2.5 (+0.9, -0.7) ×10^-3 ct s^-1 RASS PSPC 3-σ upper limit: 0.03 ct s^-1 (XRT equiv count-rate) Products: Enhanced position
24 [details]	14h 03m 38.36s210.90983°	-08° 24′ 10.1″-8.40279°	8.1′′	Poor	2.0°	8.2 ks
Mean XRT rate: 1.1 (+0.6, -0.5) ×10^-3 ct s^-1 Peak XRT rate: 1.1 (+0.6, -0.5) ×10^-3 ct s^-1 RASS PSPC 3-σ upper limit: 0.02 ct s^-1 (XRT equiv count-rate) Mean XRT flux: 1.7 (+1.0, -0.7) ×10^-14 erg cm^-1s^-1 Peak XRT flux: 1.7 (+1.0, -0.7) ×10^-14 erg cm^-1s^-1 Products: Spectrum
25 [details]	14h 03m 36.14s210.90056°	-08° 27′ 57.3″-8.46592°	6.2′′	Poor	2.0°	8.2 ks
Mean XRT rate: undetermined ct s^-1 Peak XRT rate: undetermined ct s^-1 RASS PSPC 3-σ upper limit: 0.02 ct s^-1 (XRT equiv count-rate) Products: Spectrum
26 [details]	14h 03m 10.98s210.79574°	-08° 40′ 34.1″-8.67615°	6.5′′	Poor	1.8°	8.2 ks
Mean XRT rate: undetermined ct s^-1 Peak XRT rate: undetermined ct s^-1 RASS PSPC 3-σ upper limit: 7.3×10^-9 ct s^-1 (XRT equiv count-rate) Mean XRT flux: undetermined erg cm^-1s^-1 Peak XRT flux: undetermined erg cm^-1s^-1 Products: Spectrum
27 [details]	14h 03m 50.96s210.96233°	-08° 30′ 39.4″-8.51094°	6.4′′	Poor	1.9°	8.2 ks	Matches SIMBAD source: LEDA 1002801, 5.6″ away.
Mean XRT rate: undetermined ct s^-1 Peak XRT rate: undetermined ct s^-1 RASS PSPC 3-σ upper limit: 0.02 ct s^-1 (XRT equiv count-rate) Mean XRT flux: undetermined erg cm^-1s^-1 Peak XRT flux: undetermined erg cm^-1s^-1 Products: Spectrum
28 [details]	14h 03m 41.76s210.92399°	-08° 23′ 27.3″-8.39090°	7.7′′	Poor	2.1°	8.2 ks
Mean XRT rate: 1.4 (+0.7, -0.6) ×10^-3 ct s^-1 Peak XRT rate: 1.4 (+0.7, -0.6) ×10^-3 ct s^-1 RASS PSPC 3-σ upper limit: 0.10 ct s^-1 (XRT equiv count-rate) Mean XRT flux: 6.8 (+3.3, -2.6) ×10^-14 erg cm^-1s^-1 Peak XRT flux: 6.8 (+3.3, -2.6) ×10^-14 erg cm^-1s^-1 Products: Spectrum

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