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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. See the documentation for help with subscribing to or submitting Circulars.

Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
Advanced Search

To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.

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subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

28287 results found.

  1. GRB 250903A: LCO optical observation
  2. GRB 250903A: LCO optical afterglow detection
  3. GRB 250903A: SVOM/VT optical confirmation with VHF data
  4. EP250901a: Mondy, Assy and SAO RAS optical limits
  5. EP250903a: LCO candidate counterpart discovery
  6. GRB 250903A: TRT optical counterpart detection
  7. EP250903a: TRT optical observations
  8. EP250903a: Einstein Probe detection of an X-ray transient
  9. EP 250827B: Detection of supernova counterpart by LCO.
  10. GRB 250902B: SVOM/GRM observation
  11. EP250827b: SVOM/VT observation of AT 2025wkm
  12. LIGO/VIRGO/KAGRA S250818k: No evidence for radio variability of AT2025ulz in MeerKAT 3 GHz data
  13. GRB 250831A (SVOM trigger sb25083102): KAIT confirmation of stellar flare
  14. Fermi-LAT Gamma-ray Observations of IceCube-250831A
  15. GRB 250902A: Fermi GBM Detection
  16. GRB 250901A: Swift/UVOT Upper Limit
  17. IceCube-250831A: Upper limits from a search for additional neutrino events in IceCube
  18. GRB 250830B: Swift-XRT afterglow detection
  19. LIGO/Virgo/KAGRA S250902av: 1 counterpart neutrino candidate event from an IceCube neutrino search
  20. LIGO/Virgo/KAGRA S250901cb: Updated Sky localization
  21. GRB 250831A (SVOM trigger sb25083102): confirmation of a stellar flare by SVOM/VT
  22. GRB 250902A: SVOM/GRM observation
  23. EP250828a: Early near-infrared follow-up with MIRAGE on the MDM 1.3m telescope
  24. EP250901a: refined analysis of the EP-WXT and EP-FXT observations
  25. IceCube-Cascade 250828A: Upper limits from a search for additional neutrino events in IceCube
  26. GRB 250901A: SVOM/VT optical afterglow with VHF data
  27. GRB 250901A: Swift-XRT afterglow detection
  28. EP250901a: Swift-XRT observations
  29. LIGO/Virgo/KAGRA S250830bp: DECam GW-MMADS candidates
  30. GRB 250901A: LCO optical upper limit
  31. LIGO/Virgo/KAGRA S250830bp: DECam DESGW Epoch 1 Candidates
  32. EP250827b: Gemini Spectroscopy of AT 2025wkm
  33. LIGO/Virgo/KAGRA S250901cb: Identification of a GW compact binary merger candidate
  34. EP250831a: NOT optical observations and tentative afterglow candidate
  35. EP250827b: Contemporaneous detection of EP X-ray flare EP250827b and ZTF transient ZTF25abmpngy/AT2025wkm
  36. GRB 250901A: SVOM detection of a burst
  37. EP250901a: Mephisto optical upper limits
  38. GRB 250830C: GECAM-B detection
  39. EP250901a: Einstein Probe detection of an X-ray transient
  40. LIGO/Virgo/KAGRA S250830m: Updated Sky localization
  41. EP250831a: Swift-XRT observations
  42. LIGO/Virgo/KAGRA S250831cc: Coverage and upper limits from MAXI/GSC observations
  43. EP250831a: EP-WXT detection of a fast X-ray transient
  44. GRB 250831A: Swift-XRT counterpart detection
  45. GRB 250831A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  46. GRB 250831A: SVOM/VT upper limit with VHF data
  47. GRB 250831A: SVOM detection of a soft burst
  48. GRB 250830B: Swift-XRT observations
  49. EP250830a/GRB 250830B: Einstein Probe detection of an X-ray transient and Swift/XRT follow-up
  50. LIGO/Virgo/KAGRA S250830bp: Coverage and upper limits from MAXI/GSC observations
  51. LIGO/Virgo/KAGRA S250830bp GLADEnet Completeness: Potential Host Galaxies in the 90% Credible Volume
  52. LIGO/Virgo/KAGRA S250830bp: NED Galaxies in the 4-Update Localization Volume
  53. LIGO/Virgo/KAGRA S250830bp: Updated Sky localization, EM Bright Classification, and Source Classification
  54. LIGO/Virgo/KAGRA S250830bp: Identification of a GW compact binary merger candidate
  55. EP-WXT trigger 01709200994: Liverpool Telescope upper limits
  56. EP-WXT trigger 01709200994: confirmation of a stellar flare by BOOTES-6
  57. GRB 250830B: MAXI/GSC detection
  58. LIGO/Virgo/KAGRA S250830m: Identification of a GW compact binary merger candidate
  59. GRB 250830A / MAXI J0853+337: MAXI/GSC detection
  60. GRB 250828B: Swift-BAT refined analysis
  61. LIGO/Virgo/KAGRA S250725j: Observations with the NSF-DOE Vera C. Rubin Observatory
  62. LIGO/Virgo/KAGRA S250818k: MeerKAT detection of an increase in radio flux from AT2025ulz
  63. EP250828a: refined analysis of the EP-WXT and EP-FXT observations
  64. EP250828a: Optical counterpart detection with Kinder observations
  65. EP250828a: Liverpool Telescope upper limits
  66. EP250828a: Global MASTER-Net observations report
  67. EP-WXT trigger 01709200800 : KAIT optical observations
  68. EP250828a: KAIT optical upper limit
  69. EP250827a: Swift/UVOT Detection
  70. EP250828a: NOT optical counterpart confirmation
  71. EP250828a: SVOM/VT optical candidate
  72. EP250828a: Seimei/TriCCS optical counterpart detection
  73. EP250828a: Optical upper limit with Kinder observations
  74. LIGO/Virgo/KAGRA S250827fo: Updated Sky localization
  75. EP250827a: LCO observations show fading optical counterpart
  76. EP250828a: Einstein Probe detection of an X-ray transient
  77. EP250827a: Preliminary analysis of the EP-WXT and EP-FXT observations
  78. LIGO/Virgo/KAGRA S250827fo: Identification of a GW compact binary merger candidate
  79. EP250827a: confirmation of optical rebrightening with LCO
  80. GRB 250826A: SVOM/GRM observation
  81. EP250827A: An optical rebrightening was detected by LCO.
  82. EP250827a: Swift-XRT counterpart detection
  83. LIGO/Virgo/KAGRA S250827l: Updated Sky localization
  84. EP250827a: TRT optical observations
  85. EP250827a: Gemini-South redshift z = 1.613
  86. EP250827a: Einstein Probe detection of an X-ray transient
  87. LIGO/Virgo/KAGRA S250827l: Identification of a GW compact binary merger candidate
  88. GRB 250806A: HiPERCAM/GTC limits on a possible supernova
  89. LIGO/Virgo/KAGRA S250818k: SAO RAS BTA z-band observations of AT2025ulz
  90. Fermi GRB 250824B: Global MASTER-Net observations report
  91. LIGO/Virgo/KAGRA S250818k: nature of the AT2025ulz/ZTF25abjmnnps OT
  92. LIGO/Virgo/KAGRA S250818k: Pan-STARRS imaging confirms re-brightening of SN2025ulz
  93. GRB 250823A: Swift-BAT refined analysis
  94. LIGO/Virgo/KAGRA S250818k: MASTER predicovery limits of the AT2025ulz/ZTF25abjmnps KN candidate
  95. LIGO/Virgo/KAGRA S250818k: ENGRAVE observations of SN 2025ulz as a type II supernova
  96. GRB 250823A: Swift-XRT refined Analysis
  97. EP250821a: MeerKAT radio counterpart
  98. GRB 250823A: COLIBRÍ optical observations
  99. GRB 250823A: SVOM/VT optical observation
  100. GRB 250823A: Swift/UVOT Detection

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