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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"

32509 results found.

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

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