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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"

32508 results found.

  1. LIGO/Virgo/KAGRA S250818t: Updated Sky localization
  2. GRB 250813B: SVOM/ECLAIRs refined analysis
  3. GRB 250818A: Fermi GBM Observation
  4. GRB 250818B: SVOM/VT optical observation
  5. GRB 250814A: Further GRAWITA TNG NIR observations
  6. GRB 250818B: Swift-XRT afterglow detection
  7. GRB 250818B: GOTO optical counterpart candidate
  8. GRB 250818B: SVOM detection of a short burst
  9. LIGO/Virgo/KAGRA S250818t: Identification of a GW compact binary merger candidate
  10. sb25081602: Swift-XRT observations
  11. GRB 250816A: SVOM/GRM observation of a short burst
  12. Fermi GRB 250814B: Global MASTER-Net observations report
  13. GRB 250814A: Swift-BAT refined analysis
  14. GRB 250813B: Liverpool Telescope optical upper limits
  15. GRB 250814A: Further COLIBRÍ optical upper limit
  16. GRB 250814A: detection of the afterglow candidate with Liverpool Telescope
  17. GRB 250814A: GRAWITA TNG NIR observations
  18. GRB 250812A: SVOM/VT optical continued observation
  19. GRB 250814A: Mondy optical observations of the candidate counterpart to LVK S250814bg
  20. GRB 250813B: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  21. GRB250814A: TRT optical upper limits
  22. GRB 250814B: SVOM/GRM observation
  23. GRB 250813B: SVOM/GRM observation
  24. GRB 250814A: P200/WIRC observations of the afterglow candidate
  25. GRB 250814A: KAIT optical upper limit
  26. GRB 240814A: Fermi GBM Observation
  27. GRB 250814A: Possible afterglow candidate from P200/WIRC
  28. GRB 250813B: Fermi GBM Observation
  29. GRB 250814A: J-band upper limit from WINTER
  30. IceCube-250813A: Upper limits from a search for additional neutrino events in IceCube
  31. GRB 250813B: NOT observations of the optical afterglow
  32. GRB 250813B: SVOM/VT optical observations
  33. Subject GRB 250813B: SVOM/MXT refined analysis
  34. GRB 250814A: COLIBRÍ optical upper limit
  35. GRB 250813A: AstroSat CZTI detection
  36. LIGO/Virgo/KAGRA S250814bg: Identification of a GW compact binary merger candidate possibly associated with GRB 250814A detected by Fermi GBM and Swift BAT
  37. GRB 250813B: VLT X-shooter spectroscopic redshift z = 1.752
  38. GRB 250814A: DDOTI Optical Upper Limit
  39. GRB 250813B: EP-FXT counterpart detection
  40. Fermi-LAT Gamma-ray Observations of IceCube-250813A
  41. GRB 250813B: Swift-XRT afterglow detection
  42. GRB 250813B: SVOM/COLIBRÍ (FM-GFT) optical observations
  43. GRB 250813B: Ondrejov D50 fast decay
  44. GRB 250813B: SVOM detection of a bright long burst (Correction for GCN 41352).
  45. GRB 250813B: Ondrejov D50 optical afterglow detection
  46. LIGO/Virgo/KAGRA S250813k: Updated Sky localization
  47. EP250812a: Nickel optical upper limit
  48. GRB 250812A: VLT X-shooter spectroscopic redshift confirmation z = 2.571
  49. GRB 250812A: NTT spectroscopic redshift z = 2.57
  50. GRB250812a: STEP/T80S Indication of slow decay of afterglow
  51. EP250812a: NOT, NTT, and GS observations
  52. GRB 250812A: Swift/UVOT Detection
  53. EP250812a: COLIBRÍ detection of the VT candidate and evidence of flattening
  54. EP250812a: Liverpool Telescope upper limits
  55. EP250812a: SVOM/VT optical counterpart
  56. EP250812a: refined analysis of the EP-WXT and EP-FXT observations
  57. LIGO/Virgo/KAGRA S250813k: Identification of a GW compact binary merger candidate
  58. GRB 250812A: EP-FXT counterpart detection
  59. GRB 250812A: Swift ToO observations
  60. GRB 250807B: Swift-BAT refined analysis
  61. EP 250812a: GOTO optical upper limit
  62. GRB 250812A: Kilonova-Catcher optical afterglow detection
  63. EP250812a: Swift-XRT counterpart detection
  64. GRB 250812A: SVOM/COLIBRÍ (FM-GFT) optical observations
  65. GRB 250812A: SVOM/VT optical afterglow confirmation
  66. GRB 250812A: TRT likely optical counterpart detection
  67. GRB 250809A: Swift-BAT refined analysis
  68. Fermi-LAT Gamma-ray Observations of IceCube-250804A
  69. GRB 250807A: Swift-BAT refined analysis
  70. LIGO/Virgo/KAGRA S250810ck: Updated Sky localization and EM Bright Classification
  71. GRB 250809A: Swift/UVOT Detection
  72. LIGO/Virgo/KAGRA S250810ck: Identification of a GW compact binary merger candidate
  73. Corrected Swift-XRT Refined Analysis of GRB 250809A
  74. GRB 250807B: SVOM/VT optical observation
  75. EP250807a: EP-FXT follow-up observation upper limit
  76. GRB 250809A: LCOGT Optical Upper Limits
  77. GRB 250702B: Chandra X-ray Detection
  78. EP250807a: Global MASTER-Net observations report
  79. Fermi GRB 250808A: Global MASTER-Net observations report
  80. GRB 250808A: VLT X-shooter candidate counterpart
  81. GRB 250808A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  82. GRB 250808A: Fermi GBM Observation
  83. GRB 250807A: SVOM/VT optical continued observation
  84. EP-WXT trigger 01709195487: KAIT confirmation of the stellar flare
  85. GRB 250808A: SVOM detection of a long burst
  86. Konus-Wind detection of GRB 250807A
  87. GRB 250807B: Swift/UVOT Detection
  88. GRB 250807B: Kilonova-Catcher optical afterglow detection
  89. IceCube-250804A: Upper limits from a search for additional neutrino events in IceCube
  90. GRB 250807A: Swift/UVOT Detection
  91. GRB 250807B: VLT/X-Shooter spectroscopic redshift z = 1.522
  92. GRB 250806A: SVOM/MXT refined analysis
  93. GRB 250806A: SVOM/ECLAIRs refined analysis
  94. EP250807a: NTT z-band optical upper limit
  95. GRB 250806A: Mondy optical observations, and nearby bright galaxy photometry
  96. GRB 250804B: Insight-HXMT detection
  97. GRB 250807A: SVOM/GRM observation
  98. GRB 250807A: AstroSat CZTI detection of bright long burst
  99. GRB 250806A: NOT z-band upper limit and host galaxy candidate
  100. GRB 250807B: NTT optical observations

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