Swift Trigger: 1015919;

Presumed name: GRB 210104B

BAT	03^h 34^m 24.24^s, +37° 55′ 51.6″
position:	(53.601, +37.931 ± 180″)
XRT	03^h 34^m 12.89^s, +37° 55′ 48.7″
position:	(53.5537, 37.9302 ± 2.3″)
UVOT	No position available.
Galactic N_HI:	1.36×10⁰ cm^-2
Galactic E(B-V):	0.563 mag

Best RA:	03^h 34^m 12.89^s	= 53.5537 d
Best Dec:	+37° 55′ 48.7″	= 37.9302 d

Gal Lat:	-14.59
Gal Long:	155.03

Sun angle:	133.16°, -8.5 hr East of Sun

¹Sper #4 auto processing.

Galaxies within 3.33 of XRT position

	RA*	Dec*		Catalogue
6.6	53.5558	37.9311		NED
17.9	53.5479	37.9283		NED
18.5	53.5588	37.9270	B2=20.8, R1=19.9, R2=19.9	USNO-B1
24.4	53.5508	37.9367		NED
24.8	53.5608	37.9342		NED
27.5	53.5567	37.9228		NED
30.1	53.5500	37.9381		NED
38.1	53.5421	37.9250		NED
38.5	53.5417	37.9252	B2=20.7, I=18.1, R2=19.1	USNO-B1
39.6	53.5408	37.9258		NED
40.3	53.5404	37.9258		NED
41.3	53.5526	37.9188	B2=20.5, I=17.8, R1=18.8, R2=19.0	USNO-B1
41.4	53.5525	37.9186		NED
45.0	53.5558	37.9425		NED
50.3	53.5492	37.9167		NED
50.9	53.5692	37.9231		NED
53.2	53.5583	37.9158		NED
53.6	53.5367	37.9233		NED
53.6	53.5683	37.9394		NED
53.9	53.5725	37.9294		NED
54.5	53.5425	37.9425		NED
56.3	53.5412	37.9181		NED
61.4	53.5683	37.9178		NED
62.3	53.5575	37.9472		NED
63.3	53.5717	37.9408		NED
65.0	53.5329	37.9225		NED
65.6	53.5758	37.9356		NED
69.8	53.5292	37.9281		NED
71.8	53.5787	37.9269		NED
74.3	53.5751	37.9183	B1=20.4, B2=20.3, I=18.0, R1=19.0, R2=19.1	USNO-B1
74.6	53.5750	37.9183		NED
77.9	53.5679	37.9117		NED
81.0	53.5746	37.9453		NED
82.5	53.5500	37.9531		NED
84.2	53.5792	37.9419		NED
87.6	53.5684	37.9088	B1=19.6, B2=19.0, I=16.6, R1=17.1, R2=17.2	USNO-B1
87.8	53.5683	37.9089		NED
87.8	53.5783	37.9153		NED
89.9	53.5283	37.9453		NED
90.0	53.5267	37.9172		NED
90.1	53.5829	37.9403		NED
90.2	53.5429	37.9536		NED
90.7	53.5229	37.9375		NED
92.6	53.5679	37.9533		NED
93.5	53.5346	37.9514		NED
94.3	53.5854	37.9378		NED
94.7	53.5362	37.9078		NED
95.6	53.5720	37.9079	B2=20.7, I=18.4, R1=19.7, R2=19.8	USNO-B1
95.8	53.5721	37.9078		NED
96.2	53.5846	37.9192	B2=20.6, I=18.9, R1=19.7, R2=19.9	USNO-B1
99.7	53.5296	37.9100		NED
101.3	53.5667	37.9042		NED
101.9	53.5892	37.9264		NED
102.2	53.5876	37.9208	B2=19.5, R2=19.9	USNO-B1
102.6	53.5296	37.9514		NED
103.6	53.5771	37.9081		NED
104.6	53.5887	37.9217		NED
106.9	53.5383	37.9572		NED
107.2	53.5829	37.9492		NED
107.8	53.5162	37.9256		NED
108.4	53.5229	37.9122		NED
109.4	53.5637	37.9008		NED
109.6	53.5639	37.9009	B1=20.1, B2=19.9, I=17.4, R1=18.4, R2=18.2	USNO-B1
110.0	53.5771	37.9544		NED
110.2	53.5771	37.9546	I=18.3, R1=19.4, R2=19.9	USNO-B1
110.9	53.5287	37.9064		NED
111.6	53.5275	37.9533		NED
111.9	53.5900	37.9422		NED
112.7	53.5613	37.8994		NED
113.3	53.5933	37.9289		NED
113.6	53.5938	37.9292		NED
114.0	53.5563	37.8986	I=18.4, R2=19.9	USNO-B1
114.4	53.5562	37.8986		NED
115.4	53.5943	37.9304	I=18.3, R2=19.9	USNO-B1
115.6	53.5938	37.9253		NED
115.7	53.5940	37.9252	B1=16.8, B2=16.8, I=14.7, R1=15.0, R2=15.3	USNO-B1
117.7	53.5287	37.9042		NED
118.0	53.5250	37.9539		NED
118.0	53.5925	37.9189		NED
118.2	53.5248	37.9538	I=18.2, R2=19.9	USNO-B1
118.4	53.5400	37.9611		NED
118.7	53.5754	37.9583		NED
119.3	53.5229	37.9078		NED
119.8	53.5325	37.9592		NED
121.6	53.5675	37.9622		NED
122.0	53.5675	37.9623	I=17.8, R2=19.6	USNO-B1
123.0	53.5754	37.9006		NED
123.7	53.5958	37.9386		NED
123.8	53.5896	37.9106		NED
124.3	53.5267	37.9575		NED
124.6	53.5104	37.9356		NED
125.2	53.5808	37.9575		NED
125.7	53.5379	37.8975		NED
126.1	53.5537	37.8953		NED
126.7	53.5700	37.8975		NED
127.0	53.5921	37.9483		NED
127.3	53.5112	37.9189		NED
130.1	53.5099	37.9408	I=18.3, R2=19.9	USNO-B1
130.3	53.5983	37.9228		NED
131.4	53.5093	37.9404	I=18.2, R2=19.8	USNO-B1
131.6	53.5092	37.9406		NED
132.2	53.5175	37.9069		NED
133.3	53.5667	37.8947		NED
134.7	53.5150	37.9517		NED
135.4	53.5446	37.8933		NED
136.4	53.5938	37.9511		NED
137.6	53.5679	37.9667		NED
138.1	53.5162	37.9547		NED
138.6	53.5900	37.9558		NED
140.2	53.5467	37.8917		NED
140.2	53.5350	37.9661		NED
140.8	53.5979	37.9475		NED
141.1	53.5475	37.9692		NED
141.2	53.5042	37.9278		NED
142.0	53.5596	37.8911		NED
142.2	53.6002	37.9156	B1=17.4, B2=17.2, I=14.9, R1=15.2, R2=15.5	USNO-B1
142.2	53.6000	37.9156		NED
142.5	53.5058	37.9181		NED
142.8	53.5546	37.8906		NED
143.0	53.5183	37.9019		NED
144.9	53.5029	37.9328		NED
145.3	53.5121	37.9536		NED
146.2	53.6033	37.9406		NED
146.8	53.5987	37.9106		NED
146.9	53.5950	37.9056		NED
147.3	53.6055	37.9278	I=18.7, R2=19.9	USNO-B1
147.4	53.5992	37.9106		NED
147.5	53.6054	37.9275		NED
148.2	53.5662	37.9700		NED
148.3	53.5792	37.9661		NED
148.3	53.5792	37.9661	B2=20.3, I=18.3, R2=19.9	USNO-B1
148.6	53.5795	37.9661	I=18.4, R2=19.9	USNO-B1
150.1	53.5525	37.9719		NED
151.3	53.6063	37.9236		NED
151.4	53.6063	37.9233		NED
152.1	53.5045	37.9135	B1=20.3, B2=20.1, I=18.2, R1=19.3, R2=19.1	USNO-B1
152.1	53.5042	37.9136		NED
152.6	53.5950	37.9575		NED
153.1	53.6075	37.9303		NED
153.6	53.5522	37.8876	B2=20.3, I=18.4	USNO-B1
154.6	53.4992	37.9317		NED
154.7	53.5850	37.9653		NED
155.6	53.5008	37.9192		NED
156.2	53.6075	37.9386		NED
157.0	53.5229	37.8939		NED
157.2	53.5230	37.8939	I=18.0, R1=19.7, R2=19.6	USNO-B1
157.3	53.5921	37.8986		NED
157.6	53.6037	37.9117		NED
158.5	53.5375	37.9722		NED
158.9	53.5425	37.8869		NED
159.7	53.5700	37.9728		NED
160.1	53.5871	37.8944		NED
160.3	53.5892	37.8956		NED
160.7	53.5167	37.8964		NED
160.7	53.5558	37.9747		NED
161.7	53.6100	37.9358		NED
162.4	53.5483	37.8853		NED
162.4	53.5096	37.9589		NED
162.7	53.5017	37.9114		NED
162.8	53.5967	37.9603		NED
162.8	53.5483	37.8853		NED
163.2	53.5302	37.8888	B2=20.1, I=18.4	USNO-B1
163.7	53.5108	37.8997		NED
164.6	53.6117	37.9306		NED
164.7	53.5293	37.8887	B2=20.6, I=18.4	USNO-B1
164.9	53.5175	37.9661		NED
165.2	53.6100	37.9419		NED
165.5	53.5629	37.8847		NED
166.8	53.6029	37.9050		NED
166.8	53.5667	37.9753		NED
167.1	53.5546	37.8839		NED
167.8	53.4967	37.9428		NED
167.8	53.5050	37.9036		NED
168.5	53.5717	37.8856		NED
170.6	53.5142	37.8944		NED
170.8	53.5721	37.9753		NED
172.9	53.5825	37.8878		NED
173.0	53.5062	37.9606		NED
173.4	53.5633	37.9778		NED
173.4	53.5525	37.9783		NED
173.6	53.5679	37.8833		NED
173.7	53.6125	37.9433		NED
173.9	53.4933	37.9383		NED
174.1	53.5680	37.8832	B2=20.7, I=18.9, R2=19.6	USNO-B1
175.3	53.5304	37.8850		NED
176.4	53.5858	37.9722		NED
178.4	53.5421	37.8814		NED
179.4	53.5271	37.8850		NED
180.8	53.5671	37.9792		NED
181.9	53.4896	37.9303		NED
181.9	53.5596	37.9806		NED
182.5	53.4925	37.9142		NED
183.3	53.6129	37.9503		NED
183.4	53.4908	37.9419		NED
183.9	53.5033	37.8978		NED
184.5	53.5100	37.8922		NED
184.5	53.4892	37.9239		NED
185.9	53.5483	37.9817		NED
186.2	53.4904	37.9169		NED
186.3	53.5486	37.9818	I=18.4, R2=19.9	USNO-B1
186.9	53.5712	37.9803		NED
187.6	53.5521	37.8781		NED
188.1	53.6163	37.9131		NED
188.3	53.5071	37.8928		NED
188.5	53.6163	37.9131		NED
189.4	53.5367	37.9811		NED
189.5	53.4992	37.9606		NED
190.4	53.5200	37.8844		NED
190.6	53.4987	37.9608		NED
190.7	53.5704	37.8789		NED
190.7	53.5279	37.8811		NED
191.3	53.6050	37.9647		NED
191.5	53.4929	37.9536		NED
192.2	53.5458	37.8772		NED
192.4	53.6087	37.9611		NED
192.9	53.4892	37.9472		NED
193.1	53.5189	37.8841	B1=20.5, I=18.4	USNO-B1
193.2	53.4893	37.9474	I=18.1, R2=19.9	USNO-B1
195.4	53.6183	37.9489		NED
195.5	53.6217	37.9219		NED
195.9	53.5117	37.9736		NED
196.4	53.5071	37.9706		NED
197.5	53.5787	37.9814		NED
198.8	53.6183	37.9089		NED
199.1	53.5604	37.9853		NED
199.4	53.5017	37.8931		NED
199.6	53.6204	37.9472		NED
199.7	53.4850	37.9422		NED

Queried APM-N, SDSS, PSCz, SSS, NED, 2MASSX, USNO-B1.

* RA/Dec in equinox J2000

Magnitudes depend on the catalogue. e.g. For Sloan, R is the Sloan r mag, not the Johnson R from APM, for example