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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. 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"

32533 results found.

  1. GRB 250809A: LCOGT Optical Upper Limits
  2. GRB 250702B: Chandra X-ray Detection
  3. EP250807a: Global MASTER-Net observations report
  4. Fermi GRB 250808A: Global MASTER-Net observations report
  5. GRB 250808A: VLT X-shooter candidate counterpart
  6. GRB 250808A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  7. GRB 250808A: Fermi GBM Observation
  8. GRB 250807A: SVOM/VT optical continued observation
  9. EP-WXT trigger 01709195487: KAIT confirmation of the stellar flare
  10. GRB 250808A: SVOM detection of a long burst
  11. Konus-Wind detection of GRB 250807A
  12. GRB 250807B: Swift/UVOT Detection
  13. GRB 250807B: Kilonova-Catcher optical afterglow detection
  14. IceCube-250804A: Upper limits from a search for additional neutrino events in IceCube
  15. GRB 250807A: Swift/UVOT Detection
  16. GRB 250807B: VLT/X-Shooter spectroscopic redshift z = 1.522
  17. GRB 250806A: SVOM/MXT refined analysis
  18. GRB 250806A: SVOM/ECLAIRs refined analysis
  19. EP250807a: NTT z-band optical upper limit
  20. GRB 250806A: Mondy optical observations, and nearby bright galaxy photometry
  21. GRB 250804B: Insight-HXMT detection
  22. GRB 250807A: SVOM/GRM observation
  23. GRB 250807A: AstroSat CZTI detection of bright long burst
  24. GRB 250806A: NOT z-band upper limit and host galaxy candidate
  25. GRB 250807B: NTT optical observations
  26. EP250807a: EP-WXT detection of a fast X-ray transient
  27. GRB 250807A: SVOM/VT optical observation
  28. EP250806a: Upper limit from Fermi-GBM Observations
  29. GRB 250805A: Kilonova-Catcher optical upper limits
  30. EP250806a:SVOM/VT refined analysis
  31. GRB 250805A: Swift/UVOT Upper Limits
  32. GRB 250806A: Swift/UVOT U-band detection
  33. EP250806a: Liverpool telescope optical upper limit
  34. GRB 250806A: EP-FXT observation
  35. EP#01709198415/EP250806a: Swift-XRT observations
  36. EP250806a: Global MASTER-Net observations report
  37. EP250802a: EP-FXT follow-up observation
  38. EP250806a: refined analysis of the EP-WXT and EP-FXT observations
  39. EP250806a: Earlier Detection of the VT Candidate by COLIBRÍ and LS
  40. EP250806a: SVOM /VT optical candidate
  41. GRB 250806A: J-band upper limit from WINTER
  42. GRB 250805A: Swift-BAT refined analysis
  43. GRB 250806A: KAIT optical upper limit
  44. GRB 250806A: SVOM/VT refined analysis
  45. EP250806a: COLIBRÍ optical upper limit
  46. GRB 250806A: Kilonova-Catcher optical upper limits
  47. GRB 250806A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  48. GRB 250806A: SVOM/VT optical upper limit
  49. GRB 250805A: SVOM/VT optical counterpart
  50. GRB 250805A: ESO/VLT observations
  51. GRB 250805A: TRT optical upper limits
  52. GRB 250804B: Tiled Swift observations
  53. EP250802a: additional Liverpool Telescope upper limits
  54. EP250730a: SVOM/VT optical upper limit
  55. EP250802a: Liverpool Telescope optical upper limits
  56. EP250802a: Global MASTER-Net observations report
  57. EP250802a: GROWTH-India Telescope optical upper limit
  58. LIGO/Virgo/KAGRA S250802dn: Updated Sky localization
  59. LIGO/Virgo/KAGRA S250802dn: Identification of a GW compact binary merger candidate
  60. LIGO/Virgo/KAGRA S250727dc: GRANDMA/OPD observations of AT2025smm
  61. GRB 250702B: SMA observations
  62. LIGO/Virgo/KAGRA S250727dc: DECam GW-MMADS candidates
  63. LIGO/Virgo/KAGRA S250725j: GOTO pre-trigger detection of AT2025sib
  64. EP250711a: CrAO and Assy optical observations
  65. LIGO/Virgo/KAGRA S250727dc: DECam DESGW Epoch 1 Candidates
  66. EP250730a: Global MASTER-Net observations report
  67. EP250730a: COLIBRÍ optical upper limit
  68. GRB 250727A: Swift-XRT afterglow confirmation and refined analysis
  69. LIGO/Virgo/KAGRA S250725j: DECam DESGW Epoch 1-2 Candidates
  70. LIGO/Virgo/KAGRA S250727dc: Swift-XRT observations, 8 X-ray sources
  71. GRB 250725A: AstroSat CZTI detection
  72. GRB 250727A: EP-FXT follow-up observation
  73. GRB 250725A: PRIME near-infrared observations
  74. LIGO/Virgo/KAGRA S250727dc: DECam GW-MMADS upper limits of AT 2025smm
  75. LIGO/Virgo/KAGRA S250727dc: PRIME J-band upper limits of AT 2025smm
  76. GRB: Clarification on Gamma-Ray Burst Naming Convention
  77. GRB 250727A: SVOM/ECLAIRs refined analysis
  78. EP-WXT trigger 01709195487: confirmation of a stellar flare by BOOTES-6 & BOOTES-7
  79. GRB 250728A: COLIBRÍ optical upper limit
  80. GRB 250728A: Fermi GBM Observation
  81. LIGO/Virgo/KAGRA S250727dc: Updated Sky localization
  82. GRB 250728A: Swift ToO observations
  83. GRB 250728A: Swift/BAT-GUANO arcminute localization of a short burst
  84. GRB 250727A: AST3-2 Upper limit
  85. LIGO/Virgo/KAGRA S250727cl: Updated Sky localization
  86. GRB 250727A: EP-FXT counterpart detection
  87. GRB250727A: SVOM/VT optical upper limit
  88. LIGO/Virgo/KAGRA S250727dc: Identification of a GW compact binary merger candidate
  89. LIGO/Virgo/KAGRA S250727cl: Identification of a GW compact binary merger candidate
  90. LIGO/Virgo/KAGRA S250725j: DECam GW-MMADS candidates
  91. LIGO/Virgo/KAGRA S250725l: Updated Sky localization
  92. LIGO/Virgo/KAGRA S250726ak: Updated Sky localization
  93. LIGO/Virgo/KAGRA S250726ak: Identification of a GW compact binary merger candidate
  94. GRB 250725A: Fermi GBM Observation
  95. LIGO/Virgo/KAGRA S250725j: Updated Sky localization
  96. GRB 250725A: Swift-BAT refined analysis
  97. Konus-Wind detection of GRB 250725A
  98. GRB 250725A: SVOM/GRM observation
  99. GRB 250725A: Global MASTER-Net: First Optical Synchronous Observatios of Short GRB.
  100. GRB 250725A: Swift/UVOT Upper Limits

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