GRB 190531B: Swift observation summary

Mission:	Fermi/LAT
GRB RA:	24.370°
GRB Dec:	-41.970°
GRB Err:	6.6 arcmin
T0:	2019-05-31 20:09:48 UT
Galactic:	273.50° -72.43°
Galactic N_H:	1.67× 10²⁰ cm^-2
Galactic E(B-V):	0.01625767

Sun distance:	75.81°
Sun angle:	2.94 [hr](West of Sun)
Moon distance:	53.00°
Visibility of this field.

Data analysed so far:

ObsID: 00020895001 with 5.0 ks exposure.
ObsID: 00020895002 with 2.5 ks exposure.

Source 8 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.

Probable afterglow details

A source was found which matches the afterglow criteria.

#	RA (J2000)	Dec (J2000)	Err₉₀¹	Detection Flag²	Dist from LAT pos	Exposure	Notes	Vizier
8 [details]	01h 37m 11.09s24.29620°	-41° 57′ 30.3″-41.95841°	1.6′′	Good	3.4′	7.5 ks	The source is fading with 4.0-σ significance. The source is 4.3-σ above the RASS limit.
Mean XRT rate: 0.420 (±0.011) ct s^-1 Peak XRT rate: 1.06 (±0.24) ct s^-1 RASS PSPC 3-σ upper limit: 0.03 ct s^-1 (XRT equiv count-rate) Mean XRT flux: 1.73 (±0.05) ×10^-11 erg cm^-1s^-1 Peak XRT flux: 4.4 (±1.0) ×10^-11 erg cm^-1s^-1 Products: Light curve \| Spectrum \| Enhanced position \| Expected serendipitous sources: ~1.27×10^-4 [What is this?]

¹ Radius, 90% confidence.
² Indicates how likely the source is to be real. See the 2SXPS 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 18 sources have been found in the XRT data. 3 sources match catalogued sources.

#	RA (J2000)	Dec (J2000)	Err₉₀¹	Detection Flag²	Dist from LAT pos	Exposure	Notes
1 [details]	01h 38m 01.39s24.50580°	-42° 01′ 07.2″-42.01867°	8.1′′	Poor	6.7′	7.5 ks
Mean XRT rate: 9 (+6, -4) ×10^-4 ct s^-1 Peak XRT rate: 9 (+6, -4) ×10^-4 ct s^-1 RASS PSPC 3-σ upper limit: 0.09 ct s^-1 (XRT equiv count-rate) Mean XRT flux: 2.8 (+1.6, -1.2) ×10^-14 erg cm^-1s^-1 Peak XRT flux: 2.8 (+1.6, -1.2) ×10^-14 erg cm^-1s^-1 Products: Light curve \| Spectrum \| Expected serendipitous sources: ~1.1 [What is this?]
2 [details]	01h 37m 35.55s24.39811°	-41° 56′ 49.6″-41.94711°	6.1′′	Good	1.9′	7.5 ks
Mean XRT rate: 1.9 (+0.7, -0.6) ×10^-3 ct s^-1 Peak XRT rate: 1.9 (+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: 1.5 (+0.6, -0.5) ×10^-13 erg cm^-1s^-1 Peak XRT flux: 1.5 (+0.6, -0.5) ×10^-13 erg cm^-1s^-1 Products: Light curve \| Spectrum \| Expected serendipitous sources: ~0.7 [What is this?]
3 [details]	01h 37m 36.27s24.40113°	-42° 08′ 04.2″-42.13450°	5.9′′	Good	10.0′	7.5 ks
Mean XRT rate: 2.6 (+0.9, -0.7) ×10^-3 ct s^-1 Peak XRT rate: 2.6 (+0.9, -0.7) ×10^-3 ct s^-1 RASS PSPC 3-σ upper limit: 0.11 ct s^-1 (XRT equiv count-rate) Mean XRT flux: 6.2 (+2.2, -1.8) ×10^-14 erg cm^-1s^-1 Peak XRT flux: 6.2 (+2.2, -1.8) ×10^-14 erg cm^-1s^-1 Products: Light curve \| Spectrum \| Expected serendipitous sources: ~1.0 [What is this?]
4 [details]	01h 38m 13.33s24.55554°	-42° 02′ 17.1″-42.03809°	6.1′′	Good	9.2′	7.5 ks
Mean XRT rate: 5.7 (+1.3, -1.2) ×10^-3 ct s^-1 Peak XRT rate: 6.6 (±1.7) ×10^-3 ct s^-1 RASS PSPC 3-σ upper limit: 0.03 ct s^-1 (XRT equiv count-rate) Mean XRT flux: 5.1 (±1.1) ×10^-13 erg cm^-1s^-1 Peak XRT flux: 5.9 (±1.5) ×10^-13 erg cm^-1s^-1 Products: Light curve \| Spectrum \| Expected serendipitous sources: ~0.3 [What is this?]
5 [details]	01h 37m 31.65s24.38187°	-41° 45′ 42.3″-41.76175°	5.9′′	Good	12.5′	6.9 ks	Matches SIMBAD source: [VV98] J013732.0-414548, 6.5″ away.
Mean XRT rate: 7.1 (±1.8) ×10^-3 ct s^-1 Peak XRT rate: 7.1 (±1.8) ×10^-3 ct s^-1 RASS PSPC 3-σ upper limit: 0.15 ct s^-1 (XRT equiv count-rate) Mean XRT flux: 1.8 (±0.5) ×10^-13 erg cm^-1s^-1 Peak XRT flux: 1.8 (±0.5) ×10^-13 erg cm^-1s^-1 Products: Light curve \| Spectrum \| Expected serendipitous sources: ~0.3 [What is this?]
6 [details]	01h 37m 43.86s24.43273°	-42° 08′ 32.0″-42.14223°	5.9′′	Good	10.7′	7.5 ks	This source may be affected by extended emission Matches known X-ray source: 1RXS J013741.9-420820 (from ROSAT/RASSFSC), 24.9″ away.
Mean XRT rate: 3.7 (±1.0) ×10^-3 ct s^-1 Peak XRT rate: 3.7 (±1.0) ×10^-3 ct s^-1 RASS PSPC 3-σ upper limit: 0.07 ct s^-1 (XRT equiv count-rate) Mean XRT flux: 8.4 (±2.2) ×10^-14 erg cm^-1s^-1 Peak XRT flux: 8.4 (±2.2) ×10^-14 erg cm^-1s^-1 Products: Light curve \| Spectrum \| Expected serendipitous sources: ~0.7 [What is this?]
7 [details]	01h 37m 19.19s24.32996°	-42° 05′ 08.6″-42.08573°	5.5′′	Good	7.2′	7.5 ks
Mean XRT rate: 5.7 (±1.6) ×10^-3 ct s^-1 Peak XRT rate: 5.7 (±1.6) ×10^-3 ct s^-1 RASS PSPC 3-σ upper limit: 0.09 ct s^-1 (XRT equiv count-rate) Mean XRT flux: 8.8 (±2.4) ×10^-14 erg cm^-1s^-1 Peak XRT flux: 8.8 (±2.4) ×10^-14 erg cm^-1s^-1 Products: Light curve \| Spectrum \| Expected serendipitous sources: ~0.2 [What is this?]
8 [details]	01h 37m 11.09s24.29620°	-41° 57′ 30.3″-41.95841°	1.6′′	Good	3.4′	7.5 ks	The source is fading with 4.0-σ significance. The source is 4.3-σ above the RASS limit.
Mean XRT rate: 0.420 (±0.011) ct s^-1 Peak XRT rate: 1.06 (±0.24) ct s^-1 RASS PSPC 3-σ upper limit: 0.03 ct s^-1 (XRT equiv count-rate) Mean XRT flux: 1.73 (±0.05) ×10^-11 erg cm^-1s^-1 Peak XRT flux: 4.4 (±1.0) ×10^-11 erg cm^-1s^-1 Products: Light curve \| Spectrum \| Enhanced position \| Expected serendipitous sources: ~1.27×10^-4 [What is this?]
9 [details]	01h 37m 58.78s24.49491°	-41° 53′ 08.0″-41.88555°	6.6′′	Good	7.5′	7.5 ks
Mean XRT rate: 1.3 (+0.6, -0.5) ×10^-3 ct s^-1 Peak XRT rate: 1.3 (+0.6, -0.5) ×10^-3 ct s^-1 RASS PSPC 3-σ upper limit: 0.12 ct s^-1 (XRT equiv count-rate) Mean XRT flux: 3.3 (+1.5, -1.2) ×10^-14 erg cm^-1s^-1 Peak XRT flux: 3.3 (+1.5, -1.2) ×10^-14 erg cm^-1s^-1 Products: Light curve \| Spectrum \| Expected serendipitous sources: ~1.5 [What is this?]
10 [details]	01h 38m 08.89s24.53702°	-42° 07′ 27.5″-42.12431°	9.1′′	Good	11.9′	7.5 ks
Mean XRT rate: 4.8 (±1.1) ×10^-3 ct s^-1 Peak XRT rate: 4.8 (±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: 1.9 (±0.4) ×10^-13 erg cm^-1s^-1 Peak XRT flux: 1.9 (±0.4) ×10^-13 erg cm^-1s^-1 Products: Light curve \| Spectrum \| Expected serendipitous sources: ~0.6 [What is this?]
11 [details]	01h 37m 43.36s24.43068°	-41° 49′ 59.2″-41.83311°	7.3′′	Poor	8.6′	7.5 ks
Mean XRT rate: 1.3 (+0.6, -0.5) ×10^-3 ct s^-1 Peak XRT rate: 1.3 (+0.6, -0.5) ×10^-3 ct s^-1 RASS PSPC 3-σ upper limit: 0.09 ct s^-1 (XRT equiv count-rate) Mean XRT flux: 4.2 (+2.1, -1.6) ×10^-14 erg cm^-1s^-1 Peak XRT flux: 4.2 (+2.1, -1.6) ×10^-14 erg cm^-1s^-1 Products: Light curve \| Spectrum \| Expected serendipitous sources: ~2.1 [What is this?]
12 [details]	01h 37m 39.08s24.41283°	-42° 09′ 05.7″-42.15159°	8.1′′	Poor	11.1′	5.2 ks	Matches SIMBAD source: [VV98] J013739.2-420906, 3.5″ away.
Mean XRT rate: 1.9 (+1.0, -0.8) ×10^-3 ct s^-1 Peak XRT rate: 1.9 (+1.0, -0.8) ×10^-3 ct s^-1 RASS PSPC 3-σ upper limit: 0.17 ct s^-1 (XRT equiv count-rate) Mean XRT flux: 5.9 (+3.1, -2.4) ×10^-14 erg cm^-1s^-1 Peak XRT flux: 5.9 (+3.1, -2.4) ×10^-14 erg cm^-1s^-1 Products: Light curve \| Spectrum \| Expected serendipitous sources: ~2.0 [What is this?]
13 [details]	01h 37m 46.93s24.44553°	-42° 08′ 03.4″-42.13429°	7.5′′	Poor	10.4′	7.5 ks	This source may be affected by extended emission
Mean XRT rate: 1.7 (+0.8, -0.6) ×10^-3 ct s^-1 Peak XRT rate: 1.7 (+0.8, -0.6) ×10^-3 ct s^-1 RASS PSPC 3-σ upper limit: 0.04 ct s^-1 (XRT equiv count-rate) Products: Light curve \| Expected serendipitous sources: ~2.0 [What is this?]
14 [details]	01h 37m 52.61s24.46920°	-42° 08′ 30.2″-42.14172°	9.4′′	Reasonable	11.2′	7.5 ks
Mean XRT rate: 1.9 (+0.8, -0.6) ×10^-3 ct s^-1 Peak XRT rate: 1.9 (+0.8, -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: 8.0 (+3.5, -2.8) ×10^-14 erg cm^-1s^-1 Peak XRT flux: 8.0 (+3.5, -2.8) ×10^-14 erg cm^-1s^-1 Products: Light curve \| Spectrum \| Expected serendipitous sources: ~2.1 [What is this?]
15 [details]	01h 37m 13.40s24.30583°	-41° 49′ 04.0″-41.81778°	7.2′′	Reasonable	9.6′	7.5 ks
Mean XRT rate: 1.2 (+0.7, -0.5) ×10^-3 ct s^-1 Peak XRT rate: 1.2 (+0.7, -0.5) ×10^-3 ct s^-1 RASS PSPC 3-σ upper limit: 0.03 ct s^-1 (XRT equiv count-rate) Products: Light curve \| Expected serendipitous sources: ~2.8 [What is this?]
16 [details]	01h 36m 56.47s24.23530°	-41° 55′ 42.2″-41.92840°	8.5′′	Poor	6.5′	7.5 ks
Mean XRT rate: 10 (+7, -5) ×10^-4 ct s^-1 Peak XRT rate: 10 (+7, -5) ×10^-4 ct s^-1 RASS PSPC 3-σ upper limit: 0.04 ct s^-1 (XRT equiv count-rate) Products: Light curve \| Expected serendipitous sources: ~1.2 [What is this?]
17 [details]	01h 37m 51.29s24.46373°	-42° 03′ 34.6″-42.05962°	7.8′′	Poor	6.8′	7.5 ks
Mean XRT rate: 1.0 (+0.6, -0.4) ×10^-3 ct s^-1 Peak XRT rate: 1.0 (+0.6, -0.4) ×10^-3 ct s^-1 RASS PSPC 3-σ upper limit: 0.06 ct s^-1 (XRT equiv count-rate) Mean XRT flux: 4.6 (+2.6, -2.0) ×10^-14 erg cm^-1s^-1 Peak XRT flux: 4.6 (+2.6, -2.0) ×10^-14 erg cm^-1s^-1 Products: Light curve \| Spectrum \| Expected serendipitous sources: ~1.4 [What is this?]
18 [details]	01h 37m 59.16s24.49651°	-41° 55′ 43.4″-41.92871°	7.4′′	Poor	6.2′	7.5 ks
Mean XRT rate: 6 (+5, -3) ×10^-4 ct s^-1 Peak XRT rate: 6 (+5, -3) ×10^-4 ct s^-1 RASS PSPC 3-σ upper limit: 0.02 ct s^-1 (XRT equiv count-rate) Products: Light curve \| 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.