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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"

32567 results found.

  1. GRB 250813B: Swift-XRT afterglow detection
  2. GRB 250813B: SVOM/COLIBRÍ (FM-GFT) optical observations
  3. GRB 250813B: Ondrejov D50 fast decay
  4. GRB 250813B: SVOM detection of a bright long burst (Correction for GCN 41352).
  5. GRB 250813B: Ondrejov D50 optical afterglow detection
  6. LIGO/Virgo/KAGRA S250813k: Updated Sky localization
  7. EP250812a: Nickel optical upper limit
  8. GRB 250812A: VLT X-shooter spectroscopic redshift confirmation z = 2.571
  9. GRB 250812A: NTT spectroscopic redshift z = 2.57
  10. GRB250812a: STEP/T80S Indication of slow decay of afterglow
  11. EP250812a: NOT, NTT, and GS observations
  12. GRB 250812A: Swift/UVOT Detection
  13. EP250812a: COLIBRÍ detection of the VT candidate and evidence of flattening
  14. EP250812a: Liverpool Telescope upper limits
  15. EP250812a: SVOM/VT optical counterpart
  16. EP250812a: refined analysis of the EP-WXT and EP-FXT observations
  17. LIGO/Virgo/KAGRA S250813k: Identification of a GW compact binary merger candidate
  18. GRB 250812A: EP-FXT counterpart detection
  19. GRB 250812A: Swift ToO observations
  20. GRB 250807B: Swift-BAT refined analysis
  21. EP 250812a: GOTO optical upper limit
  22. GRB 250812A: Kilonova-Catcher optical afterglow detection
  23. EP250812a: Swift-XRT counterpart detection
  24. GRB 250812A: SVOM/COLIBRÍ (FM-GFT) optical observations
  25. GRB 250812A: SVOM/VT optical afterglow confirmation
  26. GRB 250812A: TRT likely optical counterpart detection
  27. GRB 250809A: Swift-BAT refined analysis
  28. Fermi-LAT Gamma-ray Observations of IceCube-250804A
  29. GRB 250807A: Swift-BAT refined analysis
  30. LIGO/Virgo/KAGRA S250810ck: Updated Sky localization and EM Bright Classification
  31. GRB 250809A: Swift/UVOT Detection
  32. LIGO/Virgo/KAGRA S250810ck: Identification of a GW compact binary merger candidate
  33. Corrected Swift-XRT Refined Analysis of GRB 250809A
  34. GRB 250807B: SVOM/VT optical observation
  35. EP250807a: EP-FXT follow-up observation upper limit
  36. GRB 250809A: LCOGT Optical Upper Limits
  37. GRB 250702B: Chandra X-ray Detection
  38. EP250807a: Global MASTER-Net observations report
  39. Fermi GRB 250808A: Global MASTER-Net observations report
  40. GRB 250808A: VLT X-shooter candidate counterpart
  41. GRB 250808A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  42. GRB 250808A: Fermi GBM Observation
  43. GRB 250807A: SVOM/VT optical continued observation
  44. EP-WXT trigger 01709195487: KAIT confirmation of the stellar flare
  45. GRB 250808A: SVOM detection of a long burst
  46. Konus-Wind detection of GRB 250807A
  47. GRB 250807B: Swift/UVOT Detection
  48. GRB 250807B: Kilonova-Catcher optical afterglow detection
  49. IceCube-250804A: Upper limits from a search for additional neutrino events in IceCube
  50. GRB 250807A: Swift/UVOT Detection
  51. GRB 250807B: VLT/X-Shooter spectroscopic redshift z = 1.522
  52. GRB 250806A: SVOM/MXT refined analysis
  53. GRB 250806A: SVOM/ECLAIRs refined analysis
  54. EP250807a: NTT z-band optical upper limit
  55. GRB 250806A: Mondy optical observations, and nearby bright galaxy photometry
  56. GRB 250804B: Insight-HXMT detection
  57. GRB 250807A: SVOM/GRM observation
  58. GRB 250807A: AstroSat CZTI detection of bright long burst
  59. GRB 250806A: NOT z-band upper limit and host galaxy candidate
  60. GRB 250807B: NTT optical observations
  61. EP250807a: EP-WXT detection of a fast X-ray transient
  62. GRB 250807A: SVOM/VT optical observation
  63. EP250806a: Upper limit from Fermi-GBM Observations
  64. GRB 250805A: Kilonova-Catcher optical upper limits
  65. EP250806a:SVOM/VT refined analysis
  66. GRB 250805A: Swift/UVOT Upper Limits
  67. GRB 250806A: Swift/UVOT U-band detection
  68. EP250806a: Liverpool telescope optical upper limit
  69. GRB 250806A: EP-FXT observation
  70. EP#01709198415/EP250806a: Swift-XRT observations
  71. EP250806a: Global MASTER-Net observations report
  72. EP250802a: EP-FXT follow-up observation
  73. EP250806a: refined analysis of the EP-WXT and EP-FXT observations
  74. EP250806a: Earlier Detection of the VT Candidate by COLIBRÍ and LS
  75. EP250806a: SVOM /VT optical candidate
  76. GRB 250806A: J-band upper limit from WINTER
  77. GRB 250805A: Swift-BAT refined analysis
  78. GRB 250806A: KAIT optical upper limit
  79. GRB 250806A: SVOM/VT refined analysis
  80. EP250806a: COLIBRÍ optical upper limit
  81. GRB 250806A: Kilonova-Catcher optical upper limits
  82. GRB 250806A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  83. GRB 250806A: SVOM/VT optical upper limit
  84. GRB 250805A: SVOM/VT optical counterpart
  85. GRB 250805A: ESO/VLT observations
  86. GRB 250805A: TRT optical upper limits
  87. GRB 250804B: Tiled Swift observations
  88. EP250802a: additional Liverpool Telescope upper limits
  89. EP250730a: SVOM/VT optical upper limit
  90. EP250802a: Liverpool Telescope optical upper limits
  91. EP250802a: Global MASTER-Net observations report
  92. EP250802a: GROWTH-India Telescope optical upper limit
  93. LIGO/Virgo/KAGRA S250802dn: Updated Sky localization
  94. LIGO/Virgo/KAGRA S250802dn: Identification of a GW compact binary merger candidate
  95. LIGO/Virgo/KAGRA S250727dc: GRANDMA/OPD observations of AT2025smm
  96. GRB 250702B: SMA observations
  97. LIGO/Virgo/KAGRA S250727dc: DECam GW-MMADS candidates
  98. LIGO/Virgo/KAGRA S250725j: GOTO pre-trigger detection of AT2025sib
  99. EP250711a: CrAO and Assy optical observations
  100. LIGO/Virgo/KAGRA S250727dc: DECam DESGW Epoch 1 Candidates

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