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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"

32571 results found.

  1. LIGO/Virgo/KAGRA S250830m: Updated Sky localization
  2. EP250831a: EP-FXT follow-up observation
  3. EP250831a: Swift-XRT observations
  4. EP250831a: Global MASTER-Net observations report
  5. GRB 250831A (SVOM trigger sb25083102) is likely an outburst from star G 272-61
  6. GRB 250831A: Swift-XRT counterpart detection
  7. GRB 250831A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  8. GRB 250831A: SVOM/VT upper limit with VHF data
  9. EP250830a: Global MASTER-Net observations report
  10. EP250830a/GRB 250830B: Einstein Probe detection of an X-ray transient and Swift/XRT follow-up
  11. LIGO/Virgo/KAGRA S250830bp: Coverage and upper limits from MAXI/GSC observations
  12. LIGO/Virgo/KAGRA S250830bp GLADEnet Completeness: Potential Host Galaxies in the 90% Credible Volume
  13. LIGO/Virgo/KAGRA S250830bp: Updated Sky localization, EM Bright Classification, and Source Classification
  14. LIGO/Virgo/KAGRA S250830bp: Identification of a GW compact binary merger candidate
  15. EP-WXT trigger 01709200994: Liverpool Telescope upper limits
  16. GRB 250830B: Swift ToO observations
  17. LIGO/Virgo/KAGRA S250830m: Identification of a GW compact binary merger candidate
  18. GRB 250828B: Swift-BAT refined analysis
  19. EP250821a: SOAR observations
  20. EP250827a: very early ATLAS detections, starting 43 sec after the EP trigger
  21. LIGO/Virgo/KAGRA S250725j: Observations with the NSF-DOE Vera C. Rubin Observatory
  22. LIGO/Virgo/KAGRA S250818k: MeerKAT detection of an increase in radio flux from AT2025ulz
  23. EP250828a: refined analysis of the EP-WXT and EP-FXT observations
  24. EP250828a: Optical counterpart detection with Kinder observations
  25. EP250828a: Liverpool Telescope upper limits
  26. Swift GRB 250828B: Global MASTER-Net observations report
  27. EP250828a: Global MASTER-Net observations report
  28. EP-WXT trigger 01709200800 : KAIT optical observations
  29. EP250828a: KAIT optical upper limit
  30. EP250827a: Swift/UVOT Detection
  31. EP250828a: NOT optical counterpart confirmation
  32. EP250828a: SVOM/VT optical candidate
  33. EP250828a: Seimei/TriCCS optical counterpart detection
  34. EP250827a: STEP/T80S Confirmation of fading optical counterpart
  35. EP250828a: Optical upper limit with Kinder observations
  36. LIGO/Virgo/KAGRA S250827fo: Updated Sky localization
  37. LIGO/Virgo/KAGRA S250818k: uGMRT 1.3 GHz observations of AT2025ulz
  38. EP250827a: LCO observations show fading optical counterpart
  39. EP250827a: Preliminary analysis of the EP-WXT and EP-FXT observations
  40. GRID detection of GRB 250824A
  41. LIGO/Virgo/KAGRA S250827fo: Identification of a GW compact binary merger candidate
  42. EP250827A: VLT/X-shooter redshift confirmation
  43. Fermi GRB 250827A: Global MASTER-Net observations report
  44. EP250827a: confirmation of optical rebrightening with LCO
  45. EP250827a: GOTO observation of the optical afterglow
  46. GRB 250826A: SVOM/GRM observation
  47. EP250827A: An optical rebrightening was detected by LCO.
  48. EP250827a: Swift-XRT counterpart detection
  49. LIGO/Virgo/KAGRA S250827l: Updated Sky localization
  50. EP250827a: TRT optical observations
  51. EP250827a / GRB 250827A: MASTER-OAFA OT observation
  52. EP250827a: Gemini-South redshift z = 1.613
  53. EP250827a: Global MASTER-Net observations report
  54. EP250827a: Las Cumbres independent detection of the optical counterpart
  55. EP250827a: Gemini-South optical counterpart detection
  56. LIGO/Virgo/KAGRA S250827l: Identification of a GW compact binary merger candidate
  57. Fermi GRB 250826A: Global MASTER-Net observations report
  58. GRB 250806A: HiPERCAM/GTC limits on a possible supernova
  59. EP250821a: Gemini GMOS Redshift Confirmation
  60. LIGO/Virgo/KAGRA S250818k: SAO RAS BTA z-band observations of AT2025ulz
  61. LIGO/Virgo/KAGRA S250818k: GTC/OSIRIS Confirmation of Rebrightening of AT2025ulz
  62. Fermi GRB 250824B: Global MASTER-Net observations report
  63. LIGO/Virgo/KAGRA S250818k: VLA upper limits on AT2025ulz
  64. LIGO/Virgo/KAGRA S250818k: nature of the AT2025ulz/ZTF25abjmnnps OT
  65. LIGO/Virgo/KAGRA S250818k: Pan-STARRS imaging confirms re-brightening of SN2025ulz
  66. GRB 250823A: Swift-BAT refined analysis
  67. LIGO/Virgo/KAGRA S250818k: Continued Keck I LRIS spectroscopy of ZTF25abjmnps (AT2025ulz)
  68. GRB 250821B: AstroSat CZTI detection
  69. GRB 250819A: AstroSat CZTI detection
  70. LIGO/Virgo/KAGRA S250818k: FTW Observations Show Continued Reddening of AT 2025ulz
  71. LIGO/Virgo/KAGRA S250818k: MASTER predicovery limits of the AT2025ulz/ZTF25abjmnps KN candidate
  72. GRB 250821B: Insight-HXMT detection
  73. LIGO/Virgo/KAGRA S250818k: ENGRAVE observations of SN 2025ulz as a type II supernova
  74. EP250821a: MeerKAT radio counterpart
  75. EP triggers 01709200706 and 01709200707: GOTO confirmation of flaring stars
  76. LIGO/Virgo/KAGRA S250818k: Swift Observations of AT 2025ulz - Second Epoch
  77. GRB 250823A: COLIBRÍ optical observations
  78. GRB 250823A: SVOM/VT optical observation
  79. GRB 250823A: Swift/UVOT Detection
  80. GRB 250823A: NOT optical observations
  81. LIGO/Virgo/KAGRA S250818k: CFH/MegaCam follow-up observation for AT2025ulz
  82. LIGO/Virgo/KAGRA S250818k: COLIBRÍ confirmation of rebrightening of AT2025ulz
  83. GRB 250823A: Fermi GBM Observation
  84. GRB 250818B: MeerKAT Detection
  85. GRB 250823A: LCOGT Optical Detection
  86. GRB 250823A: BOOTES6/DPRT early optical detection
  87. GRB 250823A: Liverpool Telescope optical detection
  88. Konus-Wind detection of GRB 250821B
  89. LIGO/Virgo/KAGRA S250818k: Rebrightening detected with Gemini/GMOS
  90. LIGO/Virgo/KAGRA S250818k: HST nIR detection of AT 2025ulz
  91. LIGO/Virgo/KAGRA S250818k: J-GEM follow-up observation for AT2025ulz
  92. LIGO/Virgo/KAGRA S250818k: PRIME nIR observations of AT2025ulz
  93. LIGO/Virgo/KAGRA S250818k: JinShan optical observations of AT2025ulz
  94. LIGO/Virgo/KAGRA S250818k: GTC/OSIRIS Optical Detection of AT2025ulz
  95. LIGO/Virgo/Kagra S250818k: STEP/T80N upper limits on 2025ulz
  96. LIGO/Virgo/KAGRA S250818k: 3 GHz MeerKAT observations of AT2025ulz
  97. GRB 250806A: Gemini observations of host galaxy candidate
  98. IPN triangulation of GRB 250821B (long/bright)
  99. GRB 250821A: Kilonova-Catcher optical upper limits
  100. EP250821a: Swift/XRT counterpart fading

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