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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"

28244 results found.

  1. GRB 250101A: J band upper limit by SYSU 80cm telescope
  2. EPWXT01709129925: Xinglong optical observations
  3. GRB 250106A: NOT optical observations
  4. LIGO/Virgo/KAGRA S250104v: Updated Sky localization
  5. GRB 250103B: REM optical/NIR upper limits
  6. GRB 250101A: REM optical/NIR counterpart detection
  7. GRB 250106A: Swift-XRT observations
  8. GRB 250106A: SVOM/VT optical candidate
  9. The EP-WXT trigger 01709129925 is likely a flaring star
  10. GRB 250103B: Swift-XRT refined Analysis
  11. GRB 250103B: LCO/1m optical afterglow candidate detection
  12. GRB 250103A: Bassano Bresciano Observatory upper limit
  13. GRB 250103A: Swift-XRT observations
  14. GRB 250101A: 1.3m DFOT optical afterglow detection
  15. GRB 241229A: 1.3m DFOT upper limit
  16. GRB 241228B: 1.3m DFOT Optical observations
  17. GRB 241228A: 1.3m DFOT upper limit
  18. LIGO/Virgo/KAGRA S250104v: Identification of a GW compact binary merger candidate
  19. GRB 250103A: Montarrenti Observatory optical detection
  20. GRB 250101A: further LCOGT optical afterglow observations
  21. GRB 250103A: TSHAO optical upper limit
  22. GRB 250103A: Fermi GBM Observation
  23. GRB 250103B: LCOGT Optical Upper Limit
  24. IceCube-250102A: Upper limits from a search for additional neutrino events in IceCube
  25. EP250101a: Liverpool Telescope optical upper limit
  26. IceCube-250101A: Upper limits from a search for additional neutrino events in IceCube
  27. GRB 250101a: Liverpool Telescope optical follow-up
  28. GRB 250103B: Swift detection of a burst
  29. GRB 250103A: Xinglong 2.16m Optical Candidate
  30. GRB 250101B: SVOM/GRM observation
  31. GRB 250103A: GOTO optical upper limit
  32. GRB 250103A: SVOM/C-GFT optical upper limit
  33. GRB 250101A: NUTTelA-TAO / BSTI Optical Limits
  34. EP241231b: optical upper limit with the Liverpool Telescope
  35. GRB 250103A: SVOM detection of a long burst (duplicate submission)
  36. GRB 250103A: SVOM detection of a long burst
  37. EP250101a: Xinglong optical upper limit
  38. LIGO/Virgo/KAGRA S241230bd: Upper limits from Swift/BAT-GUANO
  39. GRB 250101A: Swift-BAT refined analysis
  40. GRB 250101A: further SAO RAS optical observations
  41. GRB 250101A: LCO optical counterpart detection
  42. GRB 250101A NUTTelA-TAO / BSTI Early Measurements
  43. GRB 250101A: Swift/UVOT Detection
  44. GRB 250101A: 1.6m Mephisto multi-band optical followup
  45. GRB 250101A: Swift-XRT refined Analysis
  46. GRB 250101A: Montarrenti Observatory optical observations and rebrightening
  47. GRB 250101A: LCOGT optical afterglow detection
  48. GRB 250101A: OASDG optical observations
  49. GRB 250101B: Fermi GBM Final Real-time Localization
  50. GRB 250101A: SAO RAS observations of optical brightening
  51. GRB 250101A: BOOTES-4/MET optical afterglow detection
  52. GRB 250101A: AKO Optical Afterglow Detection
  53. GRB 250101A: SAO RAS optical observations
  54. GRB 250101A: Enhanced Swift-XRT position
  55. LIGO/Virgo/KAGRA S250101k: Updated Sky localization and Source Classification
  56. GRB 250101A: SVOM/C-GFT early optical observations
  57. LIGO/Virgo/KAGRA S250101k: Upper limits from Fermi-GBM Observations
  58. GRB 250101A: Nanshan/HMT optical observations
  59. GRB 250101A : GIT optical detection
  60. GRB 250101A: GMG Optical Observation
  61. GRB 250101A: Swift detection of a burst with an optical counterpart
  62. LIGO/Virgo/KAGRA S241231du: Coverage and upper limit from MAXI/GSC observations
  63. LIGO/Virgo/KAGRA S250101k: Identification of a GW compact binary merger candidate
  64. GRB 241229B: Continued CrAO ZTSh observations
  65. LIGO/Virgo/KAGRA S241231bg: Updated NED Galaxies in the Localization Volume
  66. LIGO/Virgo/KAGRA S241231bg: Updated Sky localization and EM Bright Classification
  67. LIGO/Virgo/KAGRA S241230ev: Updated Sky localization
  68. LIGO/Virgo/KAGRA S241231bg: NED Galaxies in the Localization Volume
  69. LIGO/Virgo/KAGRA S241230bd: Updated Sky localization
  70. GRB 241228B: Multiband optical monitoring with 1.6m Mephisto
  71. GRB 241229B: SVOM/GRM observation
  72. LIGO/Virgo/KAGRA S241231bg: Identification of a GW compact binary merger candidate
  73. EP241217A: J band upper limit by SYSU 80cm telescope
  74. LIGO/Virgo/KAGRA S241230ev: Identification of a GW compact binary merger candidate
  75. GRB 241229B: SAO RAS optical upper limit
  76. GRB 241228B: SAO RAS optical observations
  77. GRB 241229A: SAO RAS optical observations
  78. IceCube-Cascade 241228A: Upper limits from a search for additional neutrino events in IceCube
  79. GRB 241229A: Swift-XRT observations
  80. EP240702a: 7DT Optical upper limits
  81. GRB 240606B: 7DT Optical upper limits
  82. LIGO/Virgo/KAGRA S241230bd: Identification of a GW compact binary merger candidate
  83. GRB 241229B: Swift-BAT refined analysis
  84. LIGO/Virgo/KAGRA S241225v: Updated Sky localization
  85. LIGO/Virgo/KAGRA S241225c: Updated Sky localization and EM Bright Classification
  86. GRB241229B: UVOT upper limits
  87. GRB 241228B: Fermi GBM Observation
  88. GRB 241228B: Swift-XRT afterglow detection
  89. GRB 241229B: Fermi GBM Observation
  90. GRB 241229B: NUTTelA-TAO / BSTI Optical Limits
  91. GRB 241228A: Mondy optical afterglow observations
  92. GRB 241229A: GOTO optical upper limits
  93. GRB 241228B: VLT/X-shooter redshift of z = 2.674
  94. GRB 241228A: NOT optical upper limits
  95. GRB 241228B: LCO optical observation
  96. GRB 241228A: Swift-BAT refined analysis
  97. GRB 241228B: Swift/BAT-GUANO localization skymap of a burst
  98. GRB 241228A: Fermi GBM Observation
  99. GRB241228B: GROWTH-India Telescope optical observations
  100. GRB 241228B: LCOGT photometry of the likely optical counterpart GOTO24jmz

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