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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.

Advanced Search Examples (click to copy):

subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

28296 results found.

  1. EP241021a: SMA radio observation
  2. GRB 250113A: SVOM/GRM observation of a long burst
  3. GRB 250107A: VZLUSAT-2 detection
  4. EP250109b: optical upper limits with the Liverpool Telescope
  5. GRB 250106A: Swift-XRT afterglow detection
  6. EP250111a: KAIT optical observations
  7. GRB 250109A / EP250109a: Mephisto optical upper limits
  8. EP250108a: Mephisto detection
  9. EP250111a: Mondy optical observation
  10. EP250108a / AT 2025kg: LCO optical observations
  11. EP250108a / AT 2025kg: Swift UVOT detections
  12. EP250108a / AT 2025kg (the "kangaroo”): VLT/X-shooter spectroscopic redshift z = 0.176 and LFBOT classification
  13. EP250111a: NOT likely optical counterpart
  14. GRB 250101B: Fermi GBM Observation
  15. GRB 250109A / EP250109a: Terskol (INASAN) and SAO RAS observations
  16. GRB 250109A / EP250109A: Swift/BAT-GUANO localization skymap of a burst
  17. GRB 250108A: Swift/XRT afterglow fading
  18. LIGO/Virgo/KAGRA S250109bi: Updated Sky localization
  19. LIGO/Virgo/KAGRA S250109f: Updated Sky localization
  20. LIGO/Virgo/KAGRA S250108eo: Updated Sky localization
  21. EP-WXT trigger EP250108a：Xinglong optical follow-up observations
  22. GRB 250101A: CMO RC-500 optical observations
  23. GRB 250109A: Fermi GBM Observation
  24. EP250108a: NOT optical observations
  25. EP-WXT trigger EP250109a：Xinglong optical follow-up observations
  26. GRB 250109a: GMG Optical Upper Limit
  27. EP250109a: Swift/UVOT non-detection
  28. IPN triangulation of GRB 250107D (short/hard)
  29. EP250108a: Liverpool Telescope likely optical counterpart
  30. GRB 250108B: Swift-BAT refined analysis
  31. GRB 250108B: 1.3m DFOT upper limit
  32. GRB 250108B: REM optical/NIR upper limits
  33. GRB 250101A: Terskol K-800 optical observations
  34. EP250109a: Swift/XRT non-detection
  35. GRB 250108A: Swift/UVOT Upper Limits
  36. LIGO/Virgo/KAGRA S250109bi: Identification of a GW compact binary merger candidate
  37. GRB 250108A: NOT optical upper limit
  38. EP250108a: EP-WXT detection of an X-ray transient
  39. LIGO/Virgo/KAGRA S250109f: Identification of a GW compact binary merger candidate
  40. GRB 250108B: Swift-XRT refined Analysis
  41. GRB 250103A: 1.6m Mephisto optical observations
  42. GRB 250108A: Swift-XRT afterglow detection
  43. GRB 250108A:SVOM/VT optical candidate
  44. LIGO/Virgo/KAGRA S250108eo: Identification of a GW compact binary merger candidate
  45. GRB 250108B: Swift/UVOT Upper Limits
  46. GRB 250103A: Swift-XRT afterglow detection
  47. GRB 250108B: Enhanced Swift-XRT position
  48. GRB 250108B: Swift detection of a burst
  49. GRB 250107A: Fermi GBM Observation
  50. GRB 250107A: Swift/BAT-GUANO arcminute localization of a burst
  51. GRB 250106A: SVOM/VT 2nd optical deep observation
  52. GRB 250101A: J band upper limit by SYSU 80cm telescope
  53. EPWXT01709129925: Xinglong optical observations
  54. GRB 250106A: NOT optical observations
  55. LIGO/Virgo/KAGRA S250104v: Updated Sky localization
  56. GRB 250103B: REM optical/NIR upper limits
  57. GRB 250101A: REM optical/NIR counterpart detection
  58. GRB 250106A: Swift-XRT observations
  59. GRB 250106A: SVOM/VT optical candidate
  60. The EP-WXT trigger 01709129925 is likely a flaring star
  61. GRB 250103B: Swift-XRT refined Analysis
  62. GRB 250103B: LCO/1m optical afterglow candidate detection
  63. GRB 250103A: Bassano Bresciano Observatory upper limit
  64. GRB 250103A: Swift-XRT observations
  65. GRB 250101A: 1.3m DFOT optical afterglow detection
  66. GRB 241229A: 1.3m DFOT upper limit
  67. GRB 241228B: 1.3m DFOT Optical observations
  68. GRB 241228A: 1.3m DFOT upper limit
  69. LIGO/Virgo/KAGRA S250104v: Identification of a GW compact binary merger candidate
  70. GRB 250103A: Montarrenti Observatory optical detection
  71. GRB 250101A: further LCOGT optical afterglow observations
  72. GRB 250103A: TSHAO optical upper limit
  73. GRB 250103A: Fermi GBM Observation
  74. GRB 250103B: LCOGT Optical Upper Limit
  75. IceCube-250102A: Upper limits from a search for additional neutrino events in IceCube
  76. EP250101a: Liverpool Telescope optical upper limit
  77. IceCube-250101A: Upper limits from a search for additional neutrino events in IceCube
  78. GRB 250101a: Liverpool Telescope optical follow-up
  79. GRB 250103B: Swift detection of a burst
  80. GRB 250103A: Xinglong 2.16m Optical Candidate
  81. GRB 250101B: SVOM/GRM observation
  82. GRB 250103A: GOTO optical upper limit
  83. GRB 250103A: SVOM/C-GFT optical upper limit
  84. GRB 250101A: NUTTelA-TAO / BSTI Optical Limits
  85. EP241231b: optical upper limit with the Liverpool Telescope
  86. GRB 250103A: SVOM detection of a long burst (duplicate submission)
  87. GRB 250103A: SVOM detection of a long burst
  88. EP250101a: Xinglong optical upper limit
  89. LIGO/Virgo/KAGRA S241230bd: Upper limits from Swift/BAT-GUANO
  90. GRB 250101A: Swift-BAT refined analysis
  91. GRB 250101A: further SAO RAS optical observations
  92. GRB 250101A: LCO optical counterpart detection
  93. GRB 250101A NUTTelA-TAO / BSTI Early Measurements
  94. GRB 250101A: Swift/UVOT Detection
  95. GRB 250101A: 1.6m Mephisto multi-band optical followup
  96. GRB 250101A: Swift-XRT refined Analysis
  97. GRB 250101A: Montarrenti Observatory optical observations and rebrightening
  98. GRB 250101A: LCOGT optical afterglow detection
  99. GRB 250101A: OASDG optical observations
  100. GRB 250101B: Fermi GBM Final Real-time Localization

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