GRB 251208B: Swift observation summary

Mission:	Fermi/LAT
GRB RA:	228.480°
GRB Dec:	+29.070°
GRB Err:	4.2 arcmin
T0:	2025-12-08 10:17:17 UT
Galactic:	44.96° +58.64°
Galactic N_H:	2.35× 10²⁰ cm^-2
Galactic E(B-V):	0.02853053

Sun distance:	57.76°
Sun angle:	1.78 [hr](West of Sun)
Moon distance:	88.50°
Visibility of this field.

Data analysed so far:

ObsID: 00021893001 with 4.8 ks exposure.

Source 1 has been manually confirmed as the GRB afterglow; data for this object are now available through the main GRB results area for this GRB.

About ToO analysis.

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Sources found so far

So far 7 sources have been found in the XRT data. 1 sources match catalogued sources.

#	RA (J2000)	Dec (J2000)	Err₉₀¹	Detection Flag²	Dist from LAT pos	Exposure	Notes
1 [details]	15h 13m 55.46s228.48108°	+29° 02′ 44.7″29.04575°	2.3′′	Good	1.5′	4.8 ks
Mean XRT rate: 5.0 (±0.4) ×10^-2 ct s^-1 Peak XRT rate: 8.3 (±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: 1.54 (±0.12) ×10^-12 erg cm^-1s^-1 Peak XRT flux: 2.6 (±0.7) ×10^-12 erg cm^-1s^-1 Products: Light curve \| Spectrum \| Enhanced position \| Expected serendipitous sources: ~0.00×10⁺⁰ [What is this?]
2 [details]	15h 13m 16.91s228.32048°	+29° 02′ 16.4″29.03790°	5.1′′	Good	8.6′	4.8 ks
Mean XRT rate: 2.9 (+1.3, -1.0) ×10^-3 ct s^-1 Peak XRT rate: 2.9 (+1.3, -1.0) ×10^-3 ct s^-1 RASS PSPC 3-σ upper limit: 6588.30 ct s^-1 (XRT equiv count-rate) Mean XRT flux: 8.3 (+3.7, -2.9) ×10^-11 erg cm^-1s^-1 Peak XRT flux: 8.3 (+3.7, -2.9) ×10^-11 erg cm^-1s^-1 Products: Spectrum \| Expected serendipitous sources: ~0.00×10⁺⁰ [What is this?]
3 [details]	15h 14m 19.35s228.58063°	+29° 08′ 03.9″29.13441°	6.6′′	Good	6.5′	4.8 ks
Mean XRT rate: 4.3 (+2.1, -1.6) ×10^-3 ct s^-1 Peak XRT rate: 4.3 (+2.1, -1.6) ×10^-3 ct s^-1 RASS PSPC 3-σ upper limit: 0.03 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 \| Expected serendipitous sources: ~0.00×10⁺⁰ [What is this?]
4 [details]	15h 13m 40.53s228.41889°	+29° 10′ 45.1″29.17920°	6.8′′	Good	7.3′	4.8 ks
Mean XRT rate: 2.20 (+1.09, -0.84) ×10^-3 ct s^-1 Peak XRT rate: 2.20 (+1.09, -0.84) ×10^-3 ct s^-1 RASS PSPC 3-σ upper limit: 2.6×10^-3 ct s^-1 (XRT equiv count-rate) Mean XRT flux: 5.4 (+2.6, -2.0) ×10^-14 erg cm^-1s^-1 Peak XRT flux: 5.4 (+2.6, -2.0) ×10^-14 erg cm^-1s^-1 Products: Spectrum \| Expected serendipitous sources: ~0.00×10⁺⁰ [What is this?]
5 [details]	15h 13m 45.08s228.43782°	+29° 01′ 48.6″29.03016°	5.4′′	Good	3.3′	4.8 ks
Mean XRT rate: 1.9 (+1.0, -0.7) ×10^-3 ct s^-1 Peak XRT rate: 1.9 (+1.0, -0.7) ×10^-3 ct s^-1 RASS PSPC 3-σ upper limit: 0.08 ct s^-1 (XRT equiv count-rate) Mean XRT flux: 2.41 (+1.23, -0.95) ×10^-13 erg cm^-1s^-1 Peak XRT flux: 2.41 (+1.23, -0.95) ×10^-13 erg cm^-1s^-1 Products: Spectrum \| Expected serendipitous sources: ~0.00×10⁺⁰ [What is this?]
6 [details]	15h 13m 07.78s228.28242°	+28° 59′ 30.3″28.99176°	7.2′′	Good	11.4′	4.8 ks	Matches SIMBAD source: LAMOST J151307.79+285925.5, 4.8″ away.
Mean XRT rate: 2.34 (+1.14, -0.88) ×10^-3 ct s^-1 Peak XRT rate: 2.34 (+1.14, -0.88) ×10^-3 ct s^-1 RASS PSPC 3-σ upper limit: 0.02 ct s^-1 (XRT equiv count-rate) Mean XRT flux: 4.4 (+2.1, -1.7) ×10^-14 erg cm^-1s^-1 Peak XRT flux: 4.4 (+2.1, -1.7) ×10^-14 erg cm^-1s^-1 Products: Spectrum \| Expected serendipitous sources: ~0.00×10⁺⁰ [What is this?]
7 [details]	15h 14m 10.26s228.54275°	+28° 57′ 23.8″28.95662°	6.3′′	Reasonable	7.6′	4.8 ks
Mean XRT rate: 1.8 (+1.0, -0.8) ×10^-3 ct s^-1 Peak XRT rate: 1.8 (+1.0, -0.8) ×10^-3 ct s^-1 RASS PSPC 3-σ upper limit: 16461.90 ct s^-1 (XRT equiv count-rate) Mean XRT flux: 4.2 (+2.3, -1.8) ×10^-11 erg cm^-1s^-1 Peak XRT flux: 4.2 (+2.3, -1.8) ×10^-11 erg cm^-1s^-1 Products: Spectrum \| Expected serendipitous sources: ~0.00×10⁺⁰ [What is this?]

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.

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Exposure map

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FITS exposure map.