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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').
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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"

32752 results found.

  1. EP250827a: very early ATLAS detections, starting 43 sec after the EP trigger
  2. LIGO/Virgo/KAGRA S250725j: Observations with the NSF-DOE Vera C. Rubin Observatory
  3. LIGO/Virgo/KAGRA S250818k: MeerKAT detection of an increase in radio flux from AT2025ulz
  4. EP250828a: refined analysis of the EP-WXT and EP-FXT observations
  5. EP250828a: Optical counterpart detection with Kinder observations
  6. EP250828a: Liverpool Telescope upper limits
  7. Swift GRB 250828B: Global MASTER-Net observations report
  8. EP250828a: Global MASTER-Net observations report
  9. EP-WXT trigger 01709200800 : KAIT optical observations
  10. EP250828a: KAIT optical upper limit
  11. EP250827a: Swift/UVOT Detection
  12. EP250828a: NOT optical counterpart confirmation
  13. EP250828a: SVOM/VT optical candidate
  14. EP250828a: Seimei/TriCCS optical counterpart detection
  15. EP250827a: STEP/T80S Confirmation of fading optical counterpart
  16. EP250828a: Optical upper limit with Kinder observations
  17. LIGO/Virgo/KAGRA S250827fo: Updated Sky localization
  18. LIGO/Virgo/KAGRA S250818k: uGMRT 1.3 GHz observations of AT2025ulz
  19. EP250827a: LCO observations show fading optical counterpart
  20. EP250827a: Preliminary analysis of the EP-WXT and EP-FXT observations
  21. GRID detection of GRB 250824A
  22. LIGO/Virgo/KAGRA S250827fo: Identification of a GW compact binary merger candidate
  23. EP250827A: VLT/X-shooter redshift confirmation
  24. Fermi GRB 250827A: Global MASTER-Net observations report
  25. EP250827a: confirmation of optical rebrightening with LCO
  26. EP250827a: GOTO observation of the optical afterglow
  27. GRB 250826A: SVOM/GRM observation
  28. EP250827A: An optical rebrightening was detected by LCO.
  29. EP250827a: Swift-XRT counterpart detection
  30. LIGO/Virgo/KAGRA S250827l: Updated Sky localization
  31. EP250827a: TRT optical observations
  32. EP250827a / GRB 250827A: MASTER-OAFA OT observation
  33. EP250827a: Gemini-South redshift z = 1.613
  34. EP250827a: Global MASTER-Net observations report
  35. EP250827a: Las Cumbres independent detection of the optical counterpart
  36. EP250827a: Gemini-South optical counterpart detection
  37. LIGO/Virgo/KAGRA S250827l: Identification of a GW compact binary merger candidate
  38. Fermi GRB 250826A: Global MASTER-Net observations report
  39. GRB 250806A: HiPERCAM/GTC limits on a possible supernova
  40. EP250821a: Gemini GMOS Redshift Confirmation
  41. LIGO/Virgo/KAGRA S250818k: SAO RAS BTA z-band observations of AT2025ulz
  42. LIGO/Virgo/KAGRA S250818k: GTC/OSIRIS Confirmation of Rebrightening of AT2025ulz
  43. Fermi GRB 250824B: Global MASTER-Net observations report
  44. LIGO/Virgo/KAGRA S250818k: VLA upper limits on AT2025ulz
  45. LIGO/Virgo/KAGRA S250818k: nature of the AT2025ulz/ZTF25abjmnnps OT
  46. LIGO/Virgo/KAGRA S250818k: Pan-STARRS imaging confirms re-brightening of SN2025ulz
  47. GRB 250823A: Swift-BAT refined analysis
  48. LIGO/Virgo/KAGRA S250818k: Continued Keck I LRIS spectroscopy of ZTF25abjmnps (AT2025ulz)
  49. GRB 250821B: AstroSat CZTI detection
  50. GRB 250819A: AstroSat CZTI detection
  51. LIGO/Virgo/KAGRA S250818k: FTW Observations Show Continued Reddening of AT 2025ulz
  52. LIGO/Virgo/KAGRA S250818k: MASTER predicovery limits of the AT2025ulz/ZTF25abjmnps KN candidate
  53. GRB 250821B: Insight-HXMT detection
  54. LIGO/Virgo/KAGRA S250818k: ENGRAVE observations of SN 2025ulz as a type II supernova
  55. EP250821a: MeerKAT radio counterpart
  56. EP triggers 01709200706 and 01709200707: GOTO confirmation of flaring stars
  57. LIGO/Virgo/KAGRA S250818k: Swift Observations of AT 2025ulz - Second Epoch
  58. GRB 250823A: COLIBRÍ optical observations
  59. GRB 250823A: SVOM/VT optical observation
  60. GRB 250823A: Swift/UVOT Detection
  61. GRB 250823A: NOT optical observations
  62. LIGO/Virgo/KAGRA S250818k: CFH/MegaCam follow-up observation for AT2025ulz
  63. LIGO/Virgo/KAGRA S250818k: COLIBRÍ confirmation of rebrightening of AT2025ulz
  64. GRB 250823A: Fermi GBM Observation
  65. GRB 250818B: MeerKAT Detection
  66. GRB 250823A: LCOGT Optical Detection
  67. GRB 250823A: BOOTES6/DPRT early optical detection
  68. GRB 250823A: Liverpool Telescope optical detection
  69. Konus-Wind detection of GRB 250821B
  70. LIGO/Virgo/KAGRA S250818k: Rebrightening detected with Gemini/GMOS
  71. LIGO/Virgo/KAGRA S250818k: HST nIR detection of AT 2025ulz
  72. LIGO/Virgo/KAGRA S250818k: J-GEM follow-up observation for AT2025ulz
  73. LIGO/Virgo/KAGRA S250818k: PRIME nIR observations of AT2025ulz
  74. LIGO/Virgo/KAGRA S250818k: JinShan optical observations of AT2025ulz
  75. LIGO/Virgo/KAGRA S250818k: GTC/OSIRIS Optical Detection of AT2025ulz
  76. LIGO/Virgo/Kagra S250818k: STEP/T80N upper limits on 2025ulz
  77. LIGO/Virgo/KAGRA S250818k: 3 GHz MeerKAT observations of AT2025ulz
  78. GRB 250806A: Gemini observations of host galaxy candidate
  79. IPN triangulation of GRB 250821B (long/bright)
  80. GRB 250821A: Kilonova-Catcher optical upper limits
  81. EP250821a: Swift/XRT counterpart fading
  82. GRB 250812A: SVOM/ECLAIRs refined analysis
  83. GRB 250821A: Swift-BAT refined analysis
  84. LIGO/Virgo/KAGRA S250818k: Pan-STARRS coverage of the skymap and candidate counterparts
  85. LIGO/Virgo/KAGRA S250818k: NOT optical observations of AT2025ulz
  86. EP250821a: Swift/UVOT further observations.
  87. EP250821a: VLT X-shooter spectroscopic redshift z = 0.577
  88. LIGO/Virgo/KAGRA S250818k: GRAWITA TNG NIR observations of AT2025ulz
  89. GRB 250821A: VLT/FORS2 Optical Observation
  90. GRB 250821A: GECAM-B detection
  91. GRB 250821B: SVOM/GRM observation
  92. EP250821a: SVOM/VT optical observation
  93. Fermi GRB 250821B: Global MASTER-Net observations report
  94. GRB 250821A: NOT z-band upper limit
  95. GRB 250821A: KAIT optical upper limit
  96. LIGO/Virgo/KAGRA S250818k: Continued fading and reddening of AT2025ulz from Keck/LRIS imaging observations
  97. Swift GRB 250821A: Global MASTER-Net observations report
  98. LIGO/Virgo/KAGRA S250818k: ENGRAVE observations of AT 2025ulz
  99. LIGO/Virgo/KAGRA S250818k : Tautenburg observations, upper limits
  100. GRB 250821A: Swift/UVOT Upper Limits

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