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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"

21842 results found.

  1. LIGO/Virgo/KAGRA S250818k : Tautenburg observations, upper limits
  2. GRB 250821A: Swift/UVOT Upper Limits
  3. EP250821a: Swift XRT and UVOT counterpart detection
  4. LIGO/Virgo/KAGRA S250818k: GOTO counterpart search and upper limits
  5. EP250821a: Preliminary analysis of the EP-WXT and EP-FXT observations
  6. GRB 250814A: CMO SAI and SAO RAS izJ observations.
  7. LIGO/Virgo/KAGRA S250818k: 10 GHz VLA observations of AT2025ulz
  8. LIGO/Virgo/KAGRA S250818k: WFST pre-discovery limits and follow-up observations of AT 2025ulz
  9. GRB 250819A: SVOM/GRM observation of a possible “long” duration type I burst
  10. LIGO/Virgo/KAGRA S250818k: WINTER J-band observations of AT 2025ulz
  11. GRB 250818B: 10 GHz VLA detection
  12. LIGO/Virgo/KAGRA S250818k: Pan-STARRS grizy-band imaging and photometry of AT2025ulz
  13. LIGO/Virgo/KAGRA S250818k: Swift observations of AT 2025ulz
  14. LIGO/Virgo/KAGRA S250818k: Multi-band Gemini GMOS Detections
  15. LIGO/Virgo/KAGRA S250818k: ATLAS pre-discovery limits for AT2025ulz
  16. GRB 250814A: Swift/UVOT Upper Limits
  17. GRB 250813B: Swift/UVOT Upper Limit
  18. GRB 250818B: FTW optical and NIR observations show reddening of the counterpart
  19. GRB 250818B: Kilonova-Catcher optical afterglow detection
  20. GRB 250818B: Liverpool Telescope optical detections
  21. LIGO/Virgo/KAGRA S250818k: Upper limits from Fermi-GBM Observations
  22. LIGO/Virgo/KAGRA S250818k: Pan-STARRS pre-detection limits for AT2025ulz
  23. LIGO/Virgo/KAGRA S250818k: Keck I LRIS spectroscopy of ZTF25abjmnps (AT2025ulz)
  24. GRB 250818B: Swift/UVOT Detection
  25. LIGO/Virgo/KAGRA S250818k: FTW Fast reddening of AT 2025ulz
  26. GRB 250818B: optical afterglow detection with Lesedi (GOTO25fzq)
  27. GRB 250818B: TRT Optical Observation
  28. Fermi GRB 250816A: Global MASTER-Net observations report
  29. GRB 250818B: SAO RAS optical observations
  30. Swift GRB 250818A: Global MASTER-Net observations report
  31. GRB 250818B: NOT optical observations
  32. LIGO/Virgo/KAGRA S250818k: FTW optical and NIR observations of AT 2025ulz
  33. Fermi trigger No 776849714: Global MASTER-Net observations report
  34. GRB 250818B: KAIT optical observations
  35. GRB 250818A: Swift/UVOT Upper Limits
  36. LIGO/Virgo/KAGRA S250818k: Candidates from the Zwicky Transient Facility
  37. GRB 250813B: SVOM/ECLAIRs refined analysis
  38. LIGO/Virgo/KAGRA S250818k: Coverage and upper limits from MAXI/GSC observations
  39. GRB 250818B: SVOM/VT optical observation
  40. GRB 250814A: Further GRAWITA TNG NIR observations
  41. GRB 250818B: Swift-XRT afterglow detection
  42. GRB 250818B: GOTO optical counterpart candidate
  43. sb25081602: Swift-XRT observations
  44. Fermi GRB 250814B: Global MASTER-Net observations report
  45. GRB 250813B: Liverpool Telescope optical upper limits
  46. GRB 250814A: detection of the afterglow candidate with Liverpool Telescope
  47. GRB 250814A: GRAWITA TNG NIR observations
  48. GRB 250812A: SVOM/VT optical continued observation
  49. GRB 250814A: Mondy optical observations of the candidate counterpart to LVK S250814bg
  50. GRB 250813B: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  51. LIGO/Virgo/KAGRA S250813k: Swift XRT observations, 2 X-ray sources
  52. GRB 250814A: P200/WIRC observations of the afterglow candidate
  53. GRB 250814A: possible optical afterglow candidate at Spanish observatories
  54. GRB 250814A: Possible afterglow candidate from P200/WIRC
  55. GRB 250814A: Optical observations with MDM Hiltner 2.4m telescope
  56. Fermi trigger No 776818276: Global MASTER-Net observations report
  57. Swift GRB250814.32: Global MASTER-Net observations report
  58. GRB 250814A: J-band upper limit from WINTER
  59. GRB 250813B: NOT observations of the optical afterglow
  60. GRB 250813B: SVOM/VT optical observations
  61. GRB 250813B: VLT X-shooter spectroscopic redshift z = 1.752
  62. GRB 250814A: DDOTI Optical Upper Limit
  63. Fermi-LAT Gamma-ray Observations of IceCube-250813A
  64. GRB 250813B: SVOM/COLIBRÍ (FM-GFT) optical observations
  65. GRB 250813B: Ondrejov D50 fast decay
  66. LIGO/Virgo/KAGRA S250813k: NED Galaxies in the 4-Update Localization Volume
  67. EP250812a: Nickel optical upper limit
  68. GRB 250812A: VLT X-shooter spectroscopic redshift confirmation z = 2.571
  69. GRB250812a: STEP/T80S Indication of slow decay of afterglow
  70. EP250812a: NOT, NTT, and GS observations
  71. GRB 250812A: Swift/UVOT Detection
  72. EP250812a: COLIBRÍ detection of the VT candidate and evidence of flattening
  73. EP250812a: SVOM/VT optical counterpart
  74. EP250812a: refined analysis of the EP-WXT and EP-FXT observations
  75. IceCube Alert 250813.14: Global MASTER-Net observations report
  76. GRB 250812A: Swift ToO observations
  77. EP 250812a: GOTO optical upper limit
  78. GRB 250812A: Kilonova-Catcher optical afterglow detection
  79. EP250812a: Swift-XRT counterpart detection
  80. GRB 250812A: SVOM/COLIBRÍ (FM-GFT) optical observations
  81. GRB 250812A: SVOM/VT optical afterglow confirmation
  82. GRB 250812A: Swift-XRT afterglow detection
  83. GRB 250812A: TRT likely optical counterpart detection
  84. Fermi-LAT Gamma-ray Observations of IceCube-250804A
  85. GRB 250809A: Swift/UVOT Detection
  86. GRB 250702B: Chandra X-ray Detection
  87. EP250807a: Global MASTER-Net observations report
  88. Fermi GRB 250808A: Global MASTER-Net observations report
  89. GRB 250808A: VLT X-shooter candidate counterpart
  90. GRB 250808A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  91. GRB 250808A: Swift-XRT candidate counterpart detection
  92. GRB 250807A: SVOM/VT optical continued observation
  93. EP-WXT trigger 01709195487: KAIT confirmation of the stellar flare
  94. GRB 250807B: Swift/UVOT Detection
  95. GRB 250807B: Kilonova-Catcher optical afterglow detection
  96. GRB 250807A: Swift/UVOT Detection
  97. GRB 250806A: SVOM/ECLAIRs refined analysis
  98. EP250807a: NTT z-band optical upper limit
  99. GRB 250806A: Mondy optical observations, and nearby bright galaxy photometry
  100. Swift GRB250807.45: Global MASTER-Net observations report

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