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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"

32493 results found.

  1. GRB 250814A: Further COLIBRÍ optical upper limit
  2. GRB 250814A: detection of the afterglow candidate with Liverpool Telescope
  3. GRB 250814A: GRAWITA TNG NIR observations
  4. GRB 250812A: SVOM/VT optical continued observation
  5. GRB 250814A: Mondy optical observations of the candidate counterpart to LVK S250814bg
  6. GRB 250813B: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  7. GRB250814A: TRT optical upper limits
  8. GRB 250814B: SVOM/GRM observation
  9. GRB 250813B: SVOM/GRM observation
  10. GRB 250814A: P200/WIRC observations of the afterglow candidate
  11. GRB 250814A: KAIT optical upper limit
  12. GRB 240814A: Fermi GBM Observation
  13. GRB 250814A: Possible afterglow candidate from P200/WIRC
  14. GRB 250813B: Fermi GBM Observation
  15. GRB 250814A: J-band upper limit from WINTER
  16. IceCube-250813A: Upper limits from a search for additional neutrino events in IceCube
  17. GRB 250813B: NOT observations of the optical afterglow
  18. GRB 250813B: SVOM/VT optical observations
  19. Subject GRB 250813B: SVOM/MXT refined analysis
  20. GRB 250814A: COLIBRÍ optical upper limit
  21. GRB 250813A: AstroSat CZTI detection
  22. LIGO/Virgo/KAGRA S250814bg: Identification of a GW compact binary merger candidate possibly associated with GRB 250814A detected by Fermi GBM and Swift BAT
  23. GRB 250813B: VLT X-shooter spectroscopic redshift z = 1.752
  24. GRB 250814A: DDOTI Optical Upper Limit
  25. GRB 250813B: EP-FXT counterpart detection
  26. Fermi-LAT Gamma-ray Observations of IceCube-250813A
  27. GRB 250813B: Swift-XRT afterglow detection
  28. GRB 250813B: SVOM/COLIBRÍ (FM-GFT) optical observations
  29. GRB 250813B: Ondrejov D50 fast decay
  30. GRB 250813B: SVOM detection of a bright long burst (Correction for GCN 41352).
  31. GRB 250813B: Ondrejov D50 optical afterglow detection
  32. LIGO/Virgo/KAGRA S250813k: Updated Sky localization
  33. EP250812a: Nickel optical upper limit
  34. GRB 250812A: VLT X-shooter spectroscopic redshift confirmation z = 2.571
  35. GRB 250812A: NTT spectroscopic redshift z = 2.57
  36. GRB250812a: STEP/T80S Indication of slow decay of afterglow
  37. EP250812a: NOT, NTT, and GS observations
  38. GRB 250812A: Swift/UVOT Detection
  39. EP250812a: COLIBRÍ detection of the VT candidate and evidence of flattening
  40. EP250812a: Liverpool Telescope upper limits
  41. EP250812a: SVOM/VT optical counterpart
  42. EP250812a: refined analysis of the EP-WXT and EP-FXT observations
  43. LIGO/Virgo/KAGRA S250813k: Identification of a GW compact binary merger candidate
  44. GRB 250812A: EP-FXT counterpart detection
  45. GRB 250812A: Swift ToO observations
  46. GRB 250807B: Swift-BAT refined analysis
  47. EP 250812a: GOTO optical upper limit
  48. GRB 250812A: Kilonova-Catcher optical afterglow detection
  49. EP250812a: Swift-XRT counterpart detection
  50. GRB 250812A: SVOM/COLIBRÍ (FM-GFT) optical observations
  51. GRB 250812A: SVOM/VT optical afterglow confirmation
  52. GRB 250812A: TRT likely optical counterpart detection
  53. GRB 250809A: Swift-BAT refined analysis
  54. Fermi-LAT Gamma-ray Observations of IceCube-250804A
  55. GRB 250807A: Swift-BAT refined analysis
  56. LIGO/Virgo/KAGRA S250810ck: Updated Sky localization and EM Bright Classification
  57. GRB 250809A: Swift/UVOT Detection
  58. LIGO/Virgo/KAGRA S250810ck: Identification of a GW compact binary merger candidate
  59. Corrected Swift-XRT Refined Analysis of GRB 250809A
  60. GRB 250807B: SVOM/VT optical observation
  61. EP250807a: EP-FXT follow-up observation upper limit
  62. GRB 250809A: LCOGT Optical Upper Limits
  63. GRB 250702B: Chandra X-ray Detection
  64. EP250807a: Global MASTER-Net observations report
  65. Fermi GRB 250808A: Global MASTER-Net observations report
  66. GRB 250808A: VLT X-shooter candidate counterpart
  67. GRB 250808A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  68. GRB 250808A: Fermi GBM Observation
  69. GRB 250807A: SVOM/VT optical continued observation
  70. EP-WXT trigger 01709195487: KAIT confirmation of the stellar flare
  71. GRB 250808A: SVOM detection of a long burst
  72. Konus-Wind detection of GRB 250807A
  73. GRB 250807B: Swift/UVOT Detection
  74. GRB 250807B: Kilonova-Catcher optical afterglow detection
  75. IceCube-250804A: Upper limits from a search for additional neutrino events in IceCube
  76. GRB 250807A: Swift/UVOT Detection
  77. GRB 250807B: VLT/X-Shooter spectroscopic redshift z = 1.522
  78. GRB 250806A: SVOM/MXT refined analysis
  79. GRB 250806A: SVOM/ECLAIRs refined analysis
  80. EP250807a: NTT z-band optical upper limit
  81. GRB 250806A: Mondy optical observations, and nearby bright galaxy photometry
  82. GRB 250804B: Insight-HXMT detection
  83. GRB 250807A: SVOM/GRM observation
  84. GRB 250807A: AstroSat CZTI detection of bright long burst
  85. GRB 250806A: NOT z-band upper limit and host galaxy candidate
  86. GRB 250807B: NTT optical observations
  87. EP250807a: EP-WXT detection of a fast X-ray transient
  88. GRB 250807A: SVOM/VT optical observation
  89. EP250806a: Upper limit from Fermi-GBM Observations
  90. GRB 250805A: Kilonova-Catcher optical upper limits
  91. EP250806a:SVOM/VT refined analysis
  92. GRB 250805A: Swift/UVOT Upper Limits
  93. GRB 250806A: Swift/UVOT U-band detection
  94. EP250806a: Liverpool telescope optical upper limit
  95. GRB 250806A: EP-FXT observation
  96. EP#01709198415/EP250806a: Swift-XRT observations
  97. EP250806a: Global MASTER-Net observations report
  98. EP250802a: EP-FXT follow-up observation
  99. EP250806a: refined analysis of the EP-WXT and EP-FXT observations
  100. EP250806a: Earlier Detection of the VT Candidate by COLIBRÍ and LS

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