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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"

32548 results found.

  1. GRB 250807B: Swift-BAT refined analysis
  2. EP 250812a: GOTO optical upper limit
  3. GRB 250812A: Kilonova-Catcher optical afterglow detection
  4. EP250812a: Swift-XRT counterpart detection
  5. GRB 250812A: SVOM/COLIBRÍ (FM-GFT) optical observations
  6. GRB 250812A: SVOM/VT optical afterglow confirmation
  7. GRB 250812A: TRT likely optical counterpart detection
  8. GRB 250809A: Swift-BAT refined analysis
  9. Fermi-LAT Gamma-ray Observations of IceCube-250804A
  10. GRB 250807A: Swift-BAT refined analysis
  11. LIGO/Virgo/KAGRA S250810ck: Updated Sky localization and EM Bright Classification
  12. GRB 250809A: Swift/UVOT Detection
  13. LIGO/Virgo/KAGRA S250810ck: Identification of a GW compact binary merger candidate
  14. Corrected Swift-XRT Refined Analysis of GRB 250809A
  15. GRB 250807B: SVOM/VT optical observation
  16. EP250807a: EP-FXT follow-up observation upper limit
  17. GRB 250809A: LCOGT Optical Upper Limits
  18. GRB 250702B: Chandra X-ray Detection
  19. EP250807a: Global MASTER-Net observations report
  20. Fermi GRB 250808A: Global MASTER-Net observations report
  21. GRB 250808A: VLT X-shooter candidate counterpart
  22. GRB 250808A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  23. GRB 250808A: Fermi GBM Observation
  24. GRB 250807A: SVOM/VT optical continued observation
  25. EP-WXT trigger 01709195487: KAIT confirmation of the stellar flare
  26. GRB 250808A: SVOM detection of a long burst
  27. Konus-Wind detection of GRB 250807A
  28. GRB 250807B: Swift/UVOT Detection
  29. GRB 250807B: Kilonova-Catcher optical afterglow detection
  30. IceCube-250804A: Upper limits from a search for additional neutrino events in IceCube
  31. GRB 250807A: Swift/UVOT Detection
  32. GRB 250807B: VLT/X-Shooter spectroscopic redshift z = 1.522
  33. GRB 250806A: SVOM/MXT refined analysis
  34. GRB 250806A: SVOM/ECLAIRs refined analysis
  35. EP250807a: NTT z-band optical upper limit
  36. GRB 250806A: Mondy optical observations, and nearby bright galaxy photometry
  37. GRB 250804B: Insight-HXMT detection
  38. GRB 250807A: SVOM/GRM observation
  39. GRB 250807A: AstroSat CZTI detection of bright long burst
  40. GRB 250806A: NOT z-band upper limit and host galaxy candidate
  41. GRB 250807B: NTT optical observations
  42. EP250807a: EP-WXT detection of a fast X-ray transient
  43. GRB 250807A: SVOM/VT optical observation
  44. EP250806a: Upper limit from Fermi-GBM Observations
  45. GRB 250805A: Kilonova-Catcher optical upper limits
  46. EP250806a:SVOM/VT refined analysis
  47. GRB 250805A: Swift/UVOT Upper Limits
  48. GRB 250806A: Swift/UVOT U-band detection
  49. EP250806a: Liverpool telescope optical upper limit
  50. GRB 250806A: EP-FXT observation
  51. EP#01709198415/EP250806a: Swift-XRT observations
  52. EP250806a: Global MASTER-Net observations report
  53. EP250802a: EP-FXT follow-up observation
  54. EP250806a: refined analysis of the EP-WXT and EP-FXT observations
  55. EP250806a: Earlier Detection of the VT Candidate by COLIBRÍ and LS
  56. EP250806a: SVOM /VT optical candidate
  57. GRB 250806A: J-band upper limit from WINTER
  58. GRB 250805A: Swift-BAT refined analysis
  59. GRB 250806A: KAIT optical upper limit
  60. GRB 250806A: SVOM/VT refined analysis
  61. EP250806a: COLIBRÍ optical upper limit
  62. GRB 250806A: Kilonova-Catcher optical upper limits
  63. GRB 250806A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  64. GRB 250806A: SVOM/VT optical upper limit
  65. GRB 250805A: SVOM/VT optical counterpart
  66. GRB 250805A: ESO/VLT observations
  67. GRB 250805A: TRT optical upper limits
  68. GRB 250804B: Tiled Swift observations
  69. EP250802a: additional Liverpool Telescope upper limits
  70. EP250730a: SVOM/VT optical upper limit
  71. EP250802a: Liverpool Telescope optical upper limits
  72. EP250802a: Global MASTER-Net observations report
  73. EP250802a: GROWTH-India Telescope optical upper limit
  74. LIGO/Virgo/KAGRA S250802dn: Updated Sky localization
  75. LIGO/Virgo/KAGRA S250802dn: Identification of a GW compact binary merger candidate
  76. LIGO/Virgo/KAGRA S250727dc: GRANDMA/OPD observations of AT2025smm
  77. GRB 250702B: SMA observations
  78. LIGO/Virgo/KAGRA S250727dc: DECam GW-MMADS candidates
  79. LIGO/Virgo/KAGRA S250725j: GOTO pre-trigger detection of AT2025sib
  80. EP250711a: CrAO and Assy optical observations
  81. LIGO/Virgo/KAGRA S250727dc: DECam DESGW Epoch 1 Candidates
  82. EP250730a: Global MASTER-Net observations report
  83. EP250730a: COLIBRÍ optical upper limit
  84. GRB 250727A: Swift-XRT afterglow confirmation and refined analysis
  85. LIGO/Virgo/KAGRA S250725j: DECam DESGW Epoch 1-2 Candidates
  86. LIGO/Virgo/KAGRA S250727dc: Swift-XRT observations, 8 X-ray sources
  87. GRB 250725A: AstroSat CZTI detection
  88. GRB 250727A: EP-FXT follow-up observation
  89. GRB 250725A: PRIME near-infrared observations
  90. LIGO/Virgo/KAGRA S250727dc: DECam GW-MMADS upper limits of AT 2025smm
  91. LIGO/Virgo/KAGRA S250727dc: PRIME J-band upper limits of AT 2025smm
  92. GRB: Clarification on Gamma-Ray Burst Naming Convention
  93. GRB 250727A: SVOM/ECLAIRs refined analysis
  94. EP-WXT trigger 01709195487: confirmation of a stellar flare by BOOTES-6 & BOOTES-7
  95. GRB 250728A: COLIBRÍ optical upper limit
  96. GRB 250728A: Fermi GBM Observation
  97. LIGO/Virgo/KAGRA S250727dc: Updated Sky localization
  98. GRB 250728A: Swift ToO observations
  99. GRB 250728A: Swift/BAT-GUANO arcminute localization of a short burst
  100. GRB 250727A: AST3-2 Upper limit

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